global warming assignment

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Global Warming 101

Everything you wanted to know about our changing climate but were too afraid to ask.

Temperatures in Beijing rose above 104 degrees Fahrenheit on July 6, 2023.

Jia Tianyong/China News Service/VCG via Getty Images

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What is global warming?

What causes global warming, how is global warming linked to extreme weather, what are the other effects of global warming, where does the united states stand in terms of global-warming contributors, is the united states doing anything to prevent global warming, is global warming too big a problem for me to help tackle.

A: Since the Industrial Revolution, the global annual temperature has increased in total by a little more than 1 degree Celsius, or about 2 degrees Fahrenheit. Between 1880—the year that accurate recordkeeping began—and 1980, it rose on average by 0.07 degrees Celsius (0.13 degrees Fahrenheit) every 10 years. Since 1981, however, the rate of increase has more than doubled: For the last 40 years, we’ve seen the global annual temperature rise by 0.18 degrees Celsius, or 0.32 degrees Fahrenheit, per decade.

The result? A planet that has never been hotter . Nine of the 10 warmest years since 1880 have occurred since 2005—and the 5 warmest years on record have all occurred since 2015. Climate change deniers have argued that there has been a “pause” or a “slowdown” in rising global temperatures, but numerous studies, including a 2018 paper published in the journal Environmental Research Letters , have disproved this claim. The impacts of global warming are already harming people around the world.

Now climate scientists have concluded that we must limit global warming to 1.5 degrees Celsius by 2040 if we are to avoid a future in which everyday life around the world is marked by its worst, most devastating effects: the extreme droughts, wildfires, floods, tropical storms, and other disasters that we refer to collectively as climate change . These effects are felt by all people in one way or another but are experienced most acutely by the underprivileged, the economically marginalized, and people of color, for whom climate change is often a key driver of poverty, displacement, hunger, and social unrest.

A: Global warming occurs when carbon dioxide (CO 2 ) and other air pollutants collect in the atmosphere and absorb sunlight and solar radiation that have bounced off the earth’s surface. Normally this radiation would escape into space, but these pollutants, which can last for years to centuries in the atmosphere, trap the heat and cause the planet to get hotter. These heat-trapping pollutants—specifically carbon dioxide, methane, nitrous oxide, water vapor, and synthetic fluorinated gases—are known as greenhouse gases, and their impact is called the greenhouse effect.

Though natural cycles and fluctuations have caused the earth’s climate to change several times over the last 800,000 years, our current era of global warming is directly attributable to human activity—specifically to our burning of fossil fuels such as coal, oil, gasoline, and natural gas, which results in the greenhouse effect. In the United States, the largest source of greenhouse gases is transportation (29 percent), followed closely by electricity production (28 percent) and industrial activity (22 percent). Learn about the natural and human causes of climate change .

Curbing dangerous climate change requires very deep cuts in emissions, as well as the use of alternatives to fossil fuels worldwide. The good news is that countries around the globe have formally committed—as part of the 2015 Paris Climate Agreement —to lower their emissions by setting new standards and crafting new policies to meet or even exceed those standards. The not-so-good news is that we’re not working fast enough. To avoid the worst impacts of climate change, scientists tell us that we need to reduce global carbon emissions by as much as 40 percent by 2030. For that to happen, the global community must take immediate, concrete steps: to decarbonize electricity generation by equitably transitioning from fossil fuel–based production to renewable energy sources like wind and solar; to electrify our cars and trucks; and to maximize energy efficiency in our buildings, appliances, and industries.

A: Scientists agree that the earth’s rising temperatures are fueling longer and hotter heat waves , more frequent droughts , heavier rainfall , and more powerful hurricanes .

In 2015, for example, scientists concluded that a lengthy drought in California—the state’s worst water shortage in 1,200 years —had been intensified by 15 to 20 percent by global warming. They also said the odds of similar droughts happening in the future had roughly doubled over the past century. And in 2016, the National Academies of Science, Engineering, and Medicine announced that we can now confidently attribute some extreme weather events, like heat waves, droughts, and heavy precipitation, directly to climate change.

The earth’s ocean temperatures are getting warmer, too—which means that tropical storms can pick up more energy. In other words, global warming has the ability to turn a category 3 storm into a more dangerous category 4 storm. In fact, scientists have found that the frequency of North Atlantic hurricanes has increased since the early 1980s, as has the number of storms that reach categories 4 and 5. The 2020 Atlantic hurricane season included a record-breaking 30 tropical storms, 6 major hurricanes, and 13 hurricanes altogether. With increased intensity come increased damage and death. The United States saw an unprecedented 22 weather and climate disasters that caused at least a billion dollars’ worth of damage in 2020, but, according to NOAA, 2017 was the costliest on record and among the deadliest as well: Taken together, that year's tropical storms (including Hurricanes Harvey, Irma, and Maria) caused nearly $300 billion in damage and led to more than 3,300 fatalities.

The impacts of global warming are being felt everywhere. Extreme heat waves have caused tens of thousands of deaths around the world in recent years. And in an alarming sign of events to come, Antarctica has lost nearly four trillion metric tons of ice since the 1990s. The rate of loss could speed up if we keep burning fossil fuels at our current pace, some experts say, causing sea levels to rise several meters in the next 50 to 150 years and wreaking havoc on coastal communities worldwide.

A: Each year scientists learn more about the consequences of global warming , and each year we also gain new evidence of its devastating impact on people and the planet. As the heat waves, droughts, and floods associated with climate change become more frequent and more intense, communities suffer and death tolls rise. If we’re unable to reduce our emissions, scientists believe that climate change could lead to the deaths of more than 250,000 people around the globe every year and force 100 million people into poverty by 2030.

Global warming is already taking a toll on the United States. And if we aren’t able to get a handle on our emissions, here’s just a smattering of what we can look forward to:

• Disappearing glaciers, early snowmelt, and severe droughts will cause more dramatic water shortages and continue to increase the risk of wildfires in the American West.
• Rising sea levels will lead to even more coastal flooding on the Eastern Seaboard, especially in Florida, and in other areas such as the Gulf of Mexico.
• Forests, farms, and cities will face troublesome new pests , heat waves, heavy downpours, and increased flooding . All of these can damage or destroy agriculture and fisheries.
• Disruption of habitats such as coral reefs and alpine meadows could drive many plant and animal species to extinction.
• Allergies, asthma, and infectious disease outbreaks will become more common due to increased growth of pollen-producing ragweed , higher levels of air pollution , and the spread of conditions favorable to pathogens and mosquitoes.

Though everyone is affected by climate change, not everyone is affected equally. Indigenous people, people of color, and the economically marginalized are typically hit the hardest. Inequities built into our housing , health care , and labor systems make these communities more vulnerable to the worst impacts of climate change—even though these same communities have done the least to contribute to it.

A: In recent years, China has taken the lead in global-warming pollution , producing about 26 percent of all CO2 emissions. The United States comes in second. Despite making up just 4 percent of the world’s population, our nation produces a sobering 13 percent of all global CO2 emissions—nearly as much as the European Union and India (third and fourth place) combined. And America is still number one, by far, in cumulative emissions over the past 150 years. As a top contributor to global warming, the United States has an obligation to help propel the world to a cleaner, safer, and more equitable future. Our responsibility matters to other countries, and it should matter to us, too.

A: We’ve started. But in order to avoid the worsening effects of climate change, we need to do a lot more—together with other countries—to reduce our dependence on fossil fuels and transition to clean energy sources.

Under the administration of President Donald Trump (a man who falsely referred to global warming as a “hoax”), the United States withdrew from the Paris Climate Agreement, rolled back or eliminated dozens of clean air protections, and opened up federally managed lands, including culturally sacred national monuments, to fossil fuel development. Although President Biden has pledged to get the country back on track, years of inaction during and before the Trump administration—and our increased understanding of global warming’s serious impacts—mean we must accelerate our efforts to reduce greenhouse gas emissions.

Despite the lack of cooperation from the Trump administration, local and state governments made great strides during this period through efforts like the American Cities Climate Challenge and ongoing collaborations like the Regional Greenhouse Gas Initiative . Meanwhile, industry and business leaders have been working with the public sector, creating and adopting new clean-energy technologies and increasing energy efficiency in buildings, appliances, and industrial processes. 

Today the American automotive industry is finding new ways to produce cars and trucks that are more fuel efficient and is committing itself to putting more and more zero-emission electric vehicles on the road. Developers, cities, and community advocates are coming together to make sure that new affordable housing is built with efficiency in mind , reducing energy consumption and lowering electric and heating bills for residents. And renewable energy continues to surge as the costs associated with its production and distribution keep falling. In 2020 renewable energy sources such as wind and solar provided more electricity than coal for the very first time in U.S. history.

President Biden has made action on global warming a high priority. On his first day in office, he recommitted the United States to the Paris Climate Agreement, sending the world community a strong signal that we were determined to join other nations in cutting our carbon pollution to support the shared goal of preventing the average global temperature from rising more than 1.5 degrees Celsius above preindustrial levels. (Scientists say we must stay below a 2-degree increase to avoid catastrophic climate impacts.) And significantly, the president has assembled a climate team of experts and advocates who have been tasked with pursuing action both abroad and at home while furthering the cause of environmental justice and investing in nature-based solutions.

A: No! While we can’t win the fight without large-scale government action at the national level , we also can’t do it without the help of individuals who are willing to use their voices, hold government and industry leaders to account, and make changes in their daily habits.

Wondering how you can be a part of the fight against global warming? Reduce your own carbon footprint by taking a few easy steps: Make conserving energy a part of your daily routine and your decisions as a consumer. When you shop for new appliances like refrigerators, washers, and dryers, look for products with the government’s ENERGY STAR ® label; they meet a higher standard for energy efficiency than the minimum federal requirements. When you buy a car, look for one with the highest gas mileage and lowest emissions. You can also reduce your emissions by taking public transportation or carpooling when possible.

And while new federal and state standards are a step in the right direction, much more needs to be done. Voice your support of climate-friendly and climate change preparedness policies, and tell your representatives that equitably transitioning from dirty fossil fuels to clean power should be a top priority—because it’s vital to building healthy, more secure communities.

You don’t have to go it alone, either. Movements across the country are showing how climate action can build community , be led by those on the front lines of its impacts, and create a future that’s equitable and just for all .

This story was originally published on March 11, 2016 and has been updated with new information and links.

This NRDC.org story is available for online republication by news media outlets or nonprofits under these conditions: The writer(s) must be credited with a byline; you must note prominently that the story was originally published by NRDC.org and link to the original; the story cannot be edited (beyond simple things such as grammar); you can’t resell the story in any form or grant republishing rights to other outlets; you can’t republish our material wholesale or automatically—you need to select stories individually; you can’t republish the photos or graphics on our site without specific permission; you should drop us a note to let us know when you’ve used one of our stories.

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Teaching Ideas

Resources for Teaching About Climate Change With The New York Times

Dozens of resources to help students understand why our planet is warming and what we can do to stop it.

By The Learning Network

How much do your students know about climate change — what causes it, what its consequences are and what we can do to stop it?

A 2022 report from the United Nations found that countries around the world are failing to live up to their commitments to fight climate change, pointing Earth toward a future marked by more intense flooding, wildfires, drought, heat waves and species extinction.

Young people in particular are feeling the effects — both physical and emotional — of a warming planet. In response to a writing prompt about extreme weather that has been intensified by climate change, teenagers told us about experiencing deadly heat waves in Washington, devastating hurricanes in North Carolina and even smoke from the California wildfires in Vermont. They’re also feeling the anxiety of facing a future that could be even worse: “How long do I have before the Earth becomes uninhabitable? I ask myself this every day,” one student wrote .

Over the years, we’ve created dozens of resources to help young people learn about climate change with New York Times articles, interactive quizzes, graphs, films and more. To mark this moment, we’re collecting 60 of them, along with selected recent Times reporting and Opinion pieces on the topic, all in one place.

To get you started, we’ve highlighted several of those resources and offered ideas for how you can use them in your classroom. Whether it’s a short video about a teenage climate activist, a math problem about electric vehicles, or a writing prompt about their diet’s carbon footprint, we hope these activities can get your students thinking and talking about climate change and inspire them to make a difference.

How are you teaching about the climate crisis, its consequences and its solutions? Let us know in the comments.

Ideas for Teaching About Climate Change With The New York Times

1. Understand climate change (and what we can do about it) with a digital children’s book.

The Times has published thousands of stories on climate change over the years, but many of them can be dense and difficult for young people to understand. Use this guide for kids to help your students learn the basics of the climate crisis and understand what choices can lead us to a bad future or a better future. We have a related lesson plan to help.

2. Assess climate choices with an interactive quiz.

What do your students know — or think they know — about the best ways to reduce their carbon footprints? In two Student Opinion prompts, we invite teenagers to test their knowledge with a mini-quiz about good climate choices or one about how much their diets contribute to climate change , and then share their results and reflections on what they learned.

3. Analyze climate change data with New York Times graphs.

Use our notice and wonder protocol to help students analyze graphs from The New York Times related to climate change. In 2019, we rounded up 24 graphs on topics such as melting ice, rising carbon emissions and global warming’s effect on humans. You can find our most recent graphs in our roundup below or by searching “climate change” in our What’s Going On in This Graph? archives.

Another option? Have students collect and analyze their own climate change data. See how a group of science and math teachers guided their classes to do just that in this Reader Idea .

4. Show a short film about the climate crisis’s impact on a vulnerable community.

Climate change will have a disproportionate effect on the world’s most vulnerable. What can we learn from them during the climate crisis? Invite students to watch the short film “ Rebuild or Leave ‘Paradise’: Climate Change Dilemma Facing a Nicaraguan Coastal Town ” about how intensifying storms are affecting the traditional way of life in the Miskito village of Haulover, and then participate in our Film Club .

If you want to explore this topic further, see our 2017 resource “ A Lesson Plan About Climate Change and the People Already Harmed by It .”

5. Use this lesson plan to explore ways to prevent the worst effects of climate change.

Every year, world leaders and activists meet to set new targets for cutting emissions to prevent the average global temperature from rising more than 1.5 degrees Celsius, the threshold beyond which the dangers of global warming grow immensely. But what will it take to get there? In this lesson , students participate in a jigsaw activity to explore seven solutions to climate change, from renewable energy and electric vehicles to nature conservation, carbon capture and more.

6. Invite students to share their thoughts, opinions and concerns with writing prompts.

“How can you not be scared of climate change? Every time you see some news on the state of the planet, can you not feel grief? I know I do,” one student wrote in response to our writing prompt, “ Do You Experience Climate Anxiety? ”

What do your students have to say about climate change? They can weigh in on this question and others about banning plastic bags , the environmental impact of plane travel , whether we should be more optimistic about the planet’s future and more. Find them all in our list of writing prompts below.

7. Apply a math concept to a real-world climate problem: gas or electric cars?

In this lesson , use the familiar formula y=mx+b to help students think through the economic and environmental costs and benefits of electric vehicles. Does “going green” mean saving some “wallet green” too?

8. Learn about climate activism with a video.

What power do ordinary people around the world have to make a difference in the climate crisis? Invite students to watch this eight-minute Opinion video about the teenage climate activist Greta Thunberg. Then, they can share what gives them hope in the fight against climate change in our related Film Club .

Students can learn more about Ms. Thunberg and her weekly climate protest in this lesson plan from 2019.

Resources for Teaching About Climate Change From The Learning Network and The New York Times

Here is a collection of selected Learning Network and New York Times resources for teaching and learning about climate change. From The Learning Network, there are lesson plans, writing prompts, films, graphs and more. And from NYTimes.com, there are related question and answer guides, as well as recent reporting and Opinion essays.

From The Learning Network

Lesson Plans

Lesson Plan: Using Statistics to Understand Extreme Heat (2022)

Lesson Plan: The Mississippi Water Crisis and What It Means for the Rest of the Nation (2022)

Lesson of the Day: ‘The Unlikely Ascent of New York’s Compost Champion’ (2022)

Lesson of the Day: ‘In the Ocean, It’s Snowing Microplastics’ (2022)

Lesson of the Day: ‘In Wisconsin: Stowing Mowers, Pleasing Bees’ (2022)

Lesson of the Day: ‘The People Who Draw Rocks’ (2022)

Lesson of the Day: ‘How Bad Is the Western Drought? Worst in 12 Centuries, Study Finds.’ (2022)

Lesson of the Day: ‘Meet Peat, the Unsung Hero of Carbon Capture’ (2022)

Lesson of the Day: ‘See How the Dixie Fire Created Its Own Weather’ (2021)

Lesson of the Day: ‘Bad Future, Better Future’ (2021)

Lesson of the Day: ‘Two Biden Priorities, Climate and Inequality, Meet on Black-Owned Farms’ (2021)

Gas or Electric? Thinking Algebraically About Car Costs, Emissions and Trade-offs (2021)

Lesson of the Day: ‘Where 2020’s Record Heat Was Felt the Most’ (2021)

Lesson of the Day: ‘50 Years of Earth Day: What’s Better Today, and What’s Worse’ (2020)

Lesson of the Day: ‘Why Does California Have So Many Wildfires?’ (2020)

Lesson of the Day: ‘Protesting Climate Change, Young People Take to Streets in a Global Strike’ (2019)

Lesson of the Day: ‘Becoming Greta: “Invisible Girl” to Global Climate Activist, With Bumps Along the Way’ (2019)

Lesson of the Day: ‘Glaciers Are Retreating. Millions Rely on Their Water.’ (2019)

Lesson of the Day: ‘Why the Wilder Storms? It’s a “Loaded Dice” Problem’ (2018)

Lesson of the Day: ‘Hotter, Drier, Hungrier: How Global Warming Punishes the World’s Poorest’ (2018)

Lesson of the Day: ‘The World Wants Air-Conditioning. That Could Warm the World.’ (2018)

A Lesson Plan About Climate Change and the People Already Harmed by It (2017)

Guest Post | Climate Change Questions for Young Citizen Scientists (2014)

Teaching About Climate Change With The New York Times (2014)

Writing Prompts

Should Students Learn About Climate Change in School? (2022)

How Far Is Too Far in the Fight Against Climate Change? (2022)

Should We Be More Optimistic About Efforts to Combat Climate Change? (2022)

Do You Experience Climate Anxiety? (2021)

How Have You Experienced Extreme Weather? (2021)

Do You Think You Make Good Climate Choices? (2021)

Should Plastic Bags Be Banned Everywhere? (2020)

Would You Change Your Eating Habits to Reduce Your Carbon Footprint? (2019)

Should We Feel Guilty When We Travel? (2019)

How Concerned Are You About Climate Change? (2018)

Should Schools Teach About Climate Change? (2018)

Film Club: ‘New Climate Promises, Same Old Global Warming’ (2022)

Film Club: ‘The Joy of Cooking (Insects)’ (2022)

Film Club: ‘Greta Thunberg Has Given Up on Politicians’ (2021)

Film Club: ‘Rebuild or Leave “Paradise”: Climate Change Dilemma Facing a Nicaraguan Coastal Town’ (2021)

Film Club: ‘“Goodbye, Earth”: A Story for Grown-Ups’ (2021)

Film Club: ‘Sinking Islands, Floating Nation’ (2018)

Teach About Climate Change With These 24 New York Times Graphs

What’s Going On in This Graph? | Calling for Climate Action

What’s Going On in This Graph? | Tree Rings and Climate

What’s Going On in This Graph? | Hotter Summers

What’s Going On in This Graph? | Endangered Biodiversity

What’s Going On in This Graph? | Extreme Temperatures

What’s Going On in This Graph? | Clean Energy Metals

What’s Going On in This Graph? | Global Carbon Emissions

What’s Going On in This Graph? | Wind and Solar Power

What’s Going On in This Graph? | Precipitation

What’s Going On in This Graph? | Gas-to-Electric Vehicle Turnover

What’s Going On in This Graph? | Growing Zones

What’s Going On in This Graph? | Global Climate Risks

What’s Going On in This Graph? | World Cities’ Air Pollution

What’s Going On in This Graph? | U.S. Air Pollution

What’s Going On in This Graph? | Climate Friendly Cars

What’s Going On in This Graph? | Climate Threats

What’s Going On in This Graph? | Global Temperature Change

What’s Going On in This Graph? | Global Water Stress Levels

What’s Going On in This Graph? | North American Bird Populations

What’s Going On in This Graph? | Dec. 11, 2019 (food and environment)

What’s Going On in This Graph? | Nov. 20, 2019 (greenhouse gas emissions)

What’s Going On in This Graph? | Oct. 9, 2019 (global temperatures)

What’s Going On in This Graph? | April 3, 2019 (first leaf appearance)

What’s Going On in This Graph? | March 13, 2019 (electricity generation)

Reader Idea: Interpreting Data to Understand Community Opinions on Climate Change

Vocabulary in Context: Mangrove Trees

Vocabulary in Context: Sustainable Architecture

On-Demand Panel for Students: Covering the Climate Crisis

From The New York Times

The Science of Climate Change Explained: Facts, Evidence and Proof (2021)

Searching for Hidden Meaning in Climate Jargon (2021)

A Crash Course on Climate Change, 50 Years After the First Earth Day (2020)

Your Questions About Food and Climate Change, Answered (2019)

Why Half a Degree of Global Warming Is a Big Deal (2018)

Climate Change Is Complex. We’ve Got Answers to Your Questions. (2017)

You Asked, Dr. Kate Marvel Answered. Browse Reader Questions on Climate Science.

Selected Recent Reporting

The New World: Envisioning Life After Climate Change (2022)

Beyond Catastrophe: A New Climate Reality Is Coming Into View (2022)

Ocean-Eaten Islands, Fire-Scarred Forests: Our Changing World in Pictures (2022)

Climate Pledges Are Falling Short, and a Chaotic Future Looks More Like Reality (2022)

U.N. Climate Talks End With a Deal to Pay Poor Nations for Damage (2022)

The World Is Falling Short of Its Climate Goals. Four Big Emitters Show Why. (2022)

Many States Omit Climate Education. These Teachers Are Trying to Slip It In. (2022)

Extreme Heat Will Change Us (2022)

To Fight Climate Change, Canada Turns to Indigenous People to Save Its Forests (2022)

The Unseen Toll of a Warming World (2022)

‘OK Doomer’ and the Climate Advocates Who Say It’s Not Too Late (2022)

6 Aspects of American Life Threatened by Climate Change (2021)

El Niño and La Niña, Explained (2021)

Wildfires Are Intensifying. Here’s Why, and What Can Be Done. (2021)

5 Things We Know About Climate Change and Hurricanes (2020)

Climate Change Is Scaring Kids. Here’s How to Talk to Them. (2019)

Losing Earth: The Decade We Almost Stopped Climate Change (2018)

Selected Recent Opinion

We Need to Rethink How to Adapt to the Climate Crisis (2022)

We Are Wasting Time on These Climate Debates. The Next Steps Are Clear. (2022)

Postcards From a World on Fire (2021)

The Disaster We Must Think About Every Day (2021)

‘He Just Cried for a While.’ This Is My Reality of Parenting During a Climate Disaster. (2021)

This Is the World Being Left to Us by Adults (2021)

Finding the Will to Stave Off a Darker Future (2021)

How to Calm Your Climate Anxiety (2021)

What Western Society Can Learn From Indigenous Communities (2021)

The Causes of Climate Change

Human activities are driving the global warming trend observed since the mid-20th century.

• The greenhouse effect is essential to life on Earth, but human-made emissions in the atmosphere are trapping and slowing heat loss to space.
• Five key greenhouse gases are carbon dioxide, nitrous oxide, methane, chlorofluorocarbons, and water vapor.
• While the Sun has played a role in past climate changes, the evidence shows the current warming cannot be explained by the Sun.

Increasing Greenhouses Gases Are Warming the Planet

Scientists attribute the global warming trend observed since the mid-20 th century to the human expansion of the "greenhouse effect" 1 — warming that results when the atmosphere traps heat radiating from Earth toward space.

Life on Earth depends on energy coming from the Sun. About half the light energy reaching Earth's atmosphere passes through the air and clouds to the surface, where it is absorbed and radiated in the form of infrared heat. About 90% of this heat is then absorbed by greenhouse gases and re-radiated, slowing heat loss to space.

Four Major Gases That Contribute to the Greenhouse Effect

Carbon dioxide.

A vital component of the atmosphere, carbon dioxide (CO 2 ) is released through natural processes (like volcanic eruptions) and through human activities, such as burning fossil fuels and deforestation.

Like many atmospheric gases, methane comes from both natural and human-caused sources. Methane comes from plant-matter breakdown in wetlands and is also released from landfills and rice farming. Livestock animals emit methane from their digestion and manure. Leaks from fossil fuel production and transportation are another major source of methane, and natural gas is 70% to 90% methane.

Nitrous Oxide

A potent greenhouse gas produced by farming practices, nitrous oxide is released during commercial and organic fertilizer production and use. Nitrous oxide also comes from burning fossil fuels and burning vegetation and has increased by 18% in the last 100 years.

Chlorofluorocarbons (CFCs)

These chemical compounds do not exist in nature – they are entirely of industrial origin. They were used as refrigerants, solvents (a substance that dissolves others), and spray can propellants.

FORCING:  Something acting upon Earth's climate that causes a change in how energy flows through it (such as long-lasting, heat-trapping gases - also known as greenhouse gases). These gases slow outgoing heat in the atmosphere and cause the planet to warm.

Another Gas That Contributes to the Greenhouse Effect:

Water vapor.

Water vapor is the most abundant greenhouse gas, but because the warming ocean increases the amount of it in our atmosphere, it is not a direct cause of climate change. Credit:  John Fowler  on  Unsplash

FEEDBACKS:  A process where something is either amplified or reduced as time goes on, such as water vapor increasing as Earth warms leading to even more warming.

Human Activity Is the Cause of Increased Greenhouse Gas Concentrations

Over the last century, burning of fossil fuels like coal and oil has increased the concentration of atmospheric carbon dioxide (CO 2 ). This increase happens because the coal or oil burning process combines carbon with oxygen in the air to make CO 2 . To a lesser extent, clearing of land for agriculture, industry, and other human activities has increased concentrations of greenhouse gases.

The industrial activities that our modern civilization depends upon have raised atmospheric carbon dioxide levels by nearly 50% since 1750 2 . This increase is due to human activities, because scientists can see a distinctive isotopic fingerprint in the atmosphere.

In its Sixth Assessment Report, the Intergovernmental Panel on Climate Change, composed of scientific experts from countries all over the world, concluded that it is unequivocal that the increase of CO 2 , methane, and nitrous oxide in the atmosphere over the industrial era is the result of human activities and that human influence is the principal driver of many changes observed across the atmosphere, ocean, cryosphere and biosphere.

"Since systematic scientific assessments began in the 1970s, the influence of human activity on the warming of the climate system has evolved from theory to established fact."

Intergovernmental Panel on Climate Change

The panel's AR6 Working Group I (WGI) Summary for Policymakers report is online at https://www.ipcc.ch/report/ar6/wg1/ .

Evidence Shows That Current Global Warming Cannot Be Explained by Solar Irradiance

Scientists use a metric called Total Solar Irradiance (TSI) to measure the changes in energy the Earth receives from the Sun. TSI incorporates the 11-year solar cycle and solar flares/storms from the Sun's surface.

Studies show that solar variability has played a role in past climate changes. For example, a decrease in solar activity coupled with increased volcanic activity helped trigger the Little Ice Age.

But several lines of evidence show that current global warming cannot be explained by changes in energy from the Sun:

• Since 1750, the average amount of energy from the Sun either remained constant or decreased slightly 3 .
• If a more active Sun caused the warming, scientists would expect warmer temperatures in all layers of the atmosphere. Instead, they have observed a cooling in the upper atmosphere and a warming at the surface and lower parts of the atmosphere. That's because greenhouse gases are slowing heat loss from the lower atmosphere.
• Climate models that include solar irradiance changes can’t reproduce the observed temperature trend over the past century or more without including a rise in greenhouse gases.

1. IPCC 6 th Assessment Report, WG1, Summary for Policy Makers, Sections A, “ The Current State of the Climate ”

IPCC 6 th Assessment Report, WG1, Technical Summary, Sections TS.1.2, TS.2.1 and TS.3.1

2. P. Friedlingstein, et al., 2022: “Global Carbon Budget 2022”, Earth System Science Data ( 11 Nov 2022): 4811–4900. https://doi.org/10.5194/essd-14-4811-2022

3. IPCC 6 th Assessment Report, WG1, Chapter 2, Section 2.2.1, “ Solar and Orbital Forcing ” IPCC 6 th Assessment Report, WG1, Chapter 7, Sections 7.3.4.4, 7.3.5.2, Figure 7.6, “ Solar ” M. Lockwood and W.T. Ball, Placing limits on long-term variations in quiet-Sun irradiance and their contribution to total solar irradiance and solar radiative forcing of climate,” Proceedings of the Royal Society A , 476, issue 2228 (24 June 2020): https://doi 10.1098/rspa.2020.0077

Header image credit: Pixabay/stevepb Four Major Gases image credit: Adobe Stock/Ilya Glovatskiy

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ENCYCLOPEDIC ENTRY

Global warming.

The causes, effects, and complexities of global warming are important to understand so that we can fight for the health of our planet.

Earth Science, Climatology

Tennessee Power Plant

Ash spews from a coal-fueled power plant in New Johnsonville, Tennessee, United States.

Photograph by Emory Kristof/ National Geographic

Global warming is the long-term warming of the planet’s overall temperature. Though this warming trend has been going on for a long time, its pace has significantly increased in the last hundred years due to the burning of fossil fuels . As the human population has increased, so has the volume of fossil fuels burned. Fossil fuels include coal, oil, and natural gas, and burning them causes what is known as the “greenhouse effect” in Earth’s atmosphere.

The greenhouse effect is when the sun’s rays penetrate the atmosphere, but when that heat is reflected off the surface cannot escape back into space. Gases produced by the burning of fossil fuels prevent the heat from leaving the atmosphere. These greenhouse gasses are carbon dioxide , chlorofluorocarbons, water vapor , methane , and nitrous oxide . The excess heat in the atmosphere has caused the average global temperature to rise overtime, otherwise known as global warming.

Global warming has presented another issue called climate change. Sometimes these phrases are used interchangeably, however, they are different. Climate change refers to changes in weather patterns and growing seasons around the world. It also refers to sea level rise caused by the expansion of warmer seas and melting ice sheets and glaciers . Global warming causes climate change, which poses a serious threat to life on Earth in the forms of widespread flooding and extreme weather. Scientists continue to study global warming and its impact on Earth.

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UN climate report: It’s ‘now or never’ to limit global warming to 1.5 degrees

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A new flagship UN report on climate change out Monday indicating that harmful carbon emissions from 2010-2019 have never been higher in human history, is proof that the world is on a “fast track” to disaster, António Guterres has warned , with scientists arguing that it’s ‘now or never’ to limit global warming to 1.5 degrees.

Reacting to the latest findings of the Intergovernmental Panel on Climate Change ( IPCC ), the UN Secretary-General insisted that unless governments everywhere reassess their energy policies, the world will be uninhabitable.

#LIVE NOW the press conference to present the #IPCC’s latest #ClimateReport, #ClimateChange 2022: Mitigation of Climate Change, the Working Group III contribution to the Sixth Assessment Report. Including a Q&A session with registered media. https://t.co/iIl81zXev7 IPCC IPCC_CH

His comments reflected the IPCC’s insistence that all countries must reduce their fossil fuel use substantially, extend access to electricity, improve energy efficiency and increase the use of alternative fuels, such as hydrogen.

Unless action is taken soon, some major cities will be under water, Mr. Guterres said in a video message, which also forecast “unprecedented heatwaves, terrifying storms, widespread water shortages and the extinction of a million species of plants and animals”.

Horror story

The UN chief added: “This is not fiction or exaggeration. It is what science tells us will result from our current energy policies. We are on a pathway to global warming of more than double the 1.5-degree (Celsius, or 2.7-degrees Fahreinheit) limit ” that was agreed in Paris in 2015.

Providing the scientific proof to back up that damning assessment, the IPCC report – written by hundreds of leading scientists and agreed by 195 countries - noted that greenhouse gas emissions generated by human activity, have increased since 2010 “across all major sectors globally”.

In an op-ed article penned for the Washington Post, Mr. Guterres described the latest IPCC report as "a litany of broken climate promises ", which revealed a "yawning gap between climate pledges, and reality."

He wrote that high-emitting governments and corporations, were not just turning a blind eye, "they are adding fuel to the flames by continuing to invest in climate-choking industries. Scientists warn that we are already perilously close to tipping points that could lead to cascading and irreversible climate effects."

Urban issue

An increasing share of emissions can be attributed to towns and cities , the report’s authors continued, adding just as worryingly, that emissions reductions clawed back in the last decade or so “have been less than emissions increases, from rising global activity levels in industry, energy supply, transport, agriculture and buildings”.

Striking a more positive note - and insisting that it is still possible to halve emissions by 2030 - the IPCC urged governments to ramp up action to curb emissions.

The UN body also welcomed the significant decrease in the cost of renewable energy sources since 2010, by as much as 85 per cent for solar and wind energy, and batteries.

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• ‘Lifeline’ of renewable energy can steer world out of climate crisis
• 8 reasons not to give up hope - and take climate action

Encouraging climate action

“We are at a crossroads. The decisions we make now can secure a liveable future,” said IPCC Chair Hoesung Lee. “ I am encouraged by climate action being taken in many countries . There are policies, regulations and market instruments that are proving effective. If these are scaled up and applied more widely and equitably, they can support deep emissions reductions and stimulate innovation.”

To limit global warming to around 1.5C (2.7°F), the IPCC report insisted that global greenhouse gas emissions would have to peak “before 2025 at the latest, and be reduced by 43 per cent by 2030”.

Methane would also need to be reduced by about a third, the report’s authors continued, adding that even if this was achieved, it was “almost inevitable that we will temporarily exceed this temperature threshold”, although the world “could  return to below it by the end of the century”.

Now or never

“ It’s now or never, if we want to limit global warming to 1.5°C (2.7°F); without immediate and deep emissions reductions across all sectors, it will be impossible ,” said Jim Skea, Co-Chair of IPCC Working Group III, which released the latest report.

Global temperatures will stabilise when carbon dioxide emissions reach net zero. For 1.5C (2.7F), this means achieving net zero carbon dioxide emissions globally in the early 2050s; for 2C (3.6°F), it is in the early 2070s, the IPCC report states.

“This assessment shows that limiting warming to around 2C (3.6F) still requires global greenhouse gas emissions to peak before 2025 at the latest, and be reduced by a quarter by 2030.”

Policy base

A great deal of importance is attached to IPCC assessments because they provide governments with scientific information that they can use to develop climate policies.

They also play a key role in international negotiations to tackle climate change.

Among the sustainable and emissions-busting solutions that are available to governments, the IPCC report emphasised that rethinking how cities and other urban areas function in future could help significantly in mitigating the worst effects of climate change.

“These (reductions) can be achieved through lower energy consumption (such as by creating compact, walkable cities), electrification of transport in combination with low-emission energy sources, and enhanced carbon uptake and storage using nature,” the report suggested. “There are options for established, rapidly growing and new cities,” it said.

Echoing that message, IPCC Working Group III Co-Chair, Priyadarshi Shukla, insisted that “the right policies, infrastructure and technology…to enable changes to our lifestyles and behaviour, can result in a 40 to 70 per cent reduction in greenhouse gas emissions by 2050. “The evidence also shows that these lifestyle changes can improve our health and wellbeing.”

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• Intergovernmental Panel on Climate Change (IPCC)

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How Exactly Does Carbon Dioxide Cause Global Warming?

Sarah Fecht

“ You Asked ” is a series where Earth Institute experts tackle reader questions on science and sustainability. Over the past few years, we’ve received a lot of questions about carbon dioxide — how it traps heat, how it can have such a big effect if it only makes up a tiny percentage of the atmosphere, and more. With the help of Jason Smerdon , a climate scientist at Columbia University’s Lamont-Doherty Earth Observatory, we answer several of those questions here.

How does carbon dioxide trap heat?

You’ve probably already read that carbon dioxide and other greenhouse gases act like a blanket or a cap, trapping some of the heat that Earth might have otherwise radiated out into space. That’s the simple answer. But how exactly do certain molecules trap heat? The answer there requires diving into physics and chemistry.

When sunlight reaches Earth, the surface absorbs some of the light’s energy and reradiates it as infrared waves, which we feel as heat. (Hold your hand over a dark rock on a warm sunny day and you can feel this phenomenon for yourself.) These infrared waves travel up into the atmosphere and will escape back into space if unimpeded.

Oxygen and nitrogen don’t interfere with infrared waves in the atmosphere. That’s because molecules are picky about the range of wavelengths that they interact with, Smerdon explained. For example, oxygen and nitrogen absorb energy that has tightly packed wavelengths of around 200 nanometers or less, whereas infrared energy travels at wider and lazier wavelengths of 700 to 1,000,000 nanometers. Those ranges don’t overlap, so to oxygen and nitrogen, it’s as if the infrared waves don’t even exist; they let the waves (and heat) pass freely through the atmosphere.

With CO2 and other greenhouse gases, it’s different. Carbon dioxide, for example, absorbs energy at a variety of wavelengths between 2,000 and 15,000 nanometers — a range that overlaps with that of infrared energy. As CO2 soaks up this infrared energy, it vibrates and re-emits the infrared energy back in all directions. About half of that energy goes out into space, and about half of it returns to Earth as heat, contributing to the ‘greenhouse effect.’

Smerdon says that the reason why some molecules absorb infrared waves and some don’t “depends on their geometry and their composition.” He explained that oxygen and nitrogen molecules are simple — they’re each made up of only two atoms of the same element — which narrows their movements and the variety of wavelengths they can interact with. But greenhouse gases like CO2 and methane are made up of three or more atoms, which gives them a larger variety of ways to stretch and bend and twist. That means they can absorb a wider range of wavelengths — including infrared waves.

How can I see for myself that CO2 absorbs heat?

As an experiment that can be done in the home or the classroom, Smerdon recommends filling one soda bottle with CO2 (perhaps from a soda machine) and filling a second bottle with ambient air. “If you expose them both to a heat lamp, the CO2 bottle will warm up much more than the bottle with just ambient air,” he says. He recommends checking the bottle temperatures with a no-touch infrared thermometer. You’ll also want to make sure that you use the same style of bottle for each, and that both bottles receive the same amount of light from the lamp. Here’s a video of a similar experiment:

A more logistically challenging experiment that Smerdon recommends involves putting an infrared camera and a candle at opposite ends of a closed tube. When the tube is filled with ambient air, the camera picks up the infrared heat from the candle clearly. But once the tube is filled with carbon dioxide, the infrared image of the flame disappears, because the CO2 in the tube absorbs and scatters the heat from the candle in all directions, and therefore blurs out the image of the candle. There are several videos of the experiment online, including this one:

Why does carbon dioxide let heat in, but not out?

Energy enters our atmosphere as visible light, whereas it tries to leave as infrared energy. In other words, “energy coming into our planet from the Sun arrives as one currency, and it leaves in another,” said Smerdon.

CO2 molecules don’t really interact with sunlight’s wavelengths. Only after the Earth absorbs sunlight and reemits the energy as infrared waves can the CO2 and other greenhouse gases absorb the energy.

How can CO2 trap so much heat if it only makes up 0.04% of the atmosphere? Aren’t the molecules spaced too far apart?

Before humans began burning fossil fuels, naturally occurring greenhouse gases helped to make Earth’s climate habitable. Without them, the planet’s average temperature would be below freezing. So we know that even very low, natural levels of carbon dioxide and other greenhouse gases can make a huge difference in Earth’s climate.

Today, CO2 levels are higher than they have been in at least 3 million years . And although they still account for only 0.04% of the atmosphere , that still adds up to billions upon billions of tons of heat-trapping gas. For example, in 2019 alone, humans dumped 36.44 billion tonnes of CO2 into the atmosphere, where it will linger for hundreds of years. So there are plenty of CO2 molecules to provide a heat-trapping blanket across the entire atmosphere.

In addition, “trace amounts of a substance can have a large impact on a system,” explains Smerdon. Borrowing an analogy from Penn State meteorology professor David Titley, Smerdon said that “If someone my size drinks two beers, my blood alcohol content will be about 0.04 percent. That is right when the human body starts to feel the effects of alcohol.” Commercial drivers with a blood alcohol content of 0.04% can be convicted for driving under the influence.

“Similarly, it doesn’t take that much cyanide to poison a person,” adds Smerdon. “It has to do with how that specific substance interacts with the larger system and what it does to influence that system.”

In the case of greenhouse gases, the planet’s temperature is a balance between how much energy comes in versus how much energy goes out. Ultimately, any increase in the amount of heat-trapping means that the Earth’s surface gets hotter. (For a more advanced discussion of the thermodynamics involved, check out this NASA page .)

If there’s more water than CO2 in the atmosphere, how do we know that water isn’t to blame for climate change?

Water is indeed a greenhouse gas. It absorbs and re-emits infrared radiation, and thus makes the planet warmer. However, Smerdon says the amount of water vapor in the atmosphere is a consequence of warming rather than a driving force, because warmer air holds more water.

“We know this on a seasonal level,” he explains. “It’s generally drier in the winter when our local atmosphere is colder, and it’s more humid in the summer when it’s warmer.”

As carbon dioxide and other greenhouse gases heat up the planet, more water evaporates into the atmosphere, which in turn raises the temperature further. However, a hypothetical villain would not be able to exacerbate climate change by trying to pump more water vapor into the atmosphere, says Smerdon. “It would all rain out because temperature determines how much moisture can actually be held by the atmosphere.”

Similarly, it makes no sense to try to remove water vapor from the atmosphere, because natural, temperature-driven evaporation from plants and bodies of water would immediately replace it. To reduce water vapor in the atmosphere, we must lower global temperatures by reducing other greenhouse gases.

If Venus has an atmosphere that’s 95% CO2, shouldn’t it be a lot hotter than Earth?

The concentration of CO2 in Venus’ atmosphere is about 2,400 times higher than that of Earth. Yet the average temperature of Venus is only about 15 times higher. What gives?

Interestingly enough, part of the answer has to do with water vapor. According to Smerdon, scientists think that long ago, Venus experienced a runaway greenhouse effect that boiled away almost all of the planet’s water — and water vapor, remember, is also a heat-trapping gas.

“It doesn’t have water vapor in its atmosphere, which is an important factor,” says Smerdon. “And then the other important factor is Venus has all these crazy sulfuric acid clouds.”

High up in Venus’ atmosphere, he explained, clouds of sulfuric acid block about 75% of incoming sunlight. That means the vast majority of sunlight never gets a chance to reach the planet’s surface, return to the atmosphere as infrared energy, and get trapped by all that CO2 in the atmosphere.

Won’t the plants, ocean, and soil just absorb all the excess CO2?

Eventually … in several thousand years or so.

Plants, the oceans, and soil are natural carbon sinks — they remove some carbon dioxide from the atmosphere and store it underground, underwater, or in roots and tree trunks. Without human activity, the vast amounts of carbon in coal, oil, and natural gas deposits would have remained stored underground and mostly separate from the rest of the carbon cycle. But by burning these fossil fuels, humans are adding a lot more carbon into the atmosphere and ocean, and the carbon sinks don’t work fast enough to clean up our mess.

It’s like watering your garden with a firehose. Even though plants absorb water, they can only do so at a set rate, and if you keep running the firehose, your yard is going to flood. Currently our atmosphere and ocean are flooded with CO2, and we can see that the carbon sinks can’t keep up because the concentrations of CO2 in the atmosphere and oceans are rising quickly .

Unfortunately, we don’t have thousands of years to wait for nature to absorb the flood of CO2. By then, billions of people would have suffered and died from the impacts of climate change; there would be mass extinctions, and our beautiful planet would become unrecognizable. We can avoid much of that damage and suffering through a combination of decarbonizing our energy supply, pulling CO2 out the atmosphere , and developing more sustainable ways of thriving.

Editor’s note (March 17, 2021): This post was updated with additional links to Youtube videos with experiments showing the effects of carbon dioxide. Enjoy!

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I’m writing a paper for my environmental class How does the cooler atmosphere transport heat Q to the warmer surface? Q = sigma•(Ts^4 -Ta^4)

If the air’s cooler than the surface, it wouldn’t.

GREAT question Joe!

The short answer:

It doesn’t. Heat always flows from higher temperature to lower temperature. If it didn’t, the 2nd Law of Thermodynamics would be violated, and entropy would decrease (as enthalpy increased).

The longer answer:

The “greenhouse gas” mechanism does not exist. The atmosphere (including CO2) provides convection cooling to the Earth’s surface. Cloud cover does *temporarily* prevent radiational cooling by reflecting radiation back to the surface. This is distinctly different than the fictitious greenhouse gas model of absorption-and-reemission. The atmosphere also distributes heat more evenly around the planet through convection heat transfer in general; this is why the planet surface doesn’t have wild temperature differences from day to night like the moon. There is NO net warming effect due to so-called greenhouse gases.

That being said, here’s what I’m NOT saying:

-I’m not saying global warming isn’t real. We are experiencing a warming trend. -I’m not saying human activity doesn’t add to this warming trend; it does. -I’m not saying trying to minimize environmental impact isn’t worthwhile. It is not only worthwhile, it is critical. -I’m not saying plants and trees do not have a net cooling effect. They do, but it is because they are endothermic from a heat balance point of view. Plants are great because they absorb energy, NOT because they happen to use CO2 to do this.

All I’m saying is that if anyone is concerned about reducing anthropogenic global warming effects, the best approach is to try to minimize waste heat.

7.5 billion humans generate a LOT of waste heat. Birth control and insulation will help. Sequestering plant food (CO2) will make the problem worse. Less CO2=less plant life=less radiant energy from the sun being used during photosynthesis.

The obvious retort here is that many actions essential if mainstream theories are correct make sense regardless of the nature, extent, cause and direction if climate change. They would help cope with a volcanic winter (e.g. that in 1816 after the Tambora eruption) and also the collapse of a major food crop. Examples include less waste, combining conservation with careful use, restoring fish stocks, growing fewer cash crops, regenerative agriculture, silviculture and reducing the impact per head and probably numbers of conventional livestock.. Instead of shovelling grain and soya down cattle they can be fed on crop residues, natural vegetation and spent brewery grain while methane-reducing feed additives like Asparogopsis taxiformis in livestock feed could give a huge cut in emissions and some boost growth.

These are all win-win options which make sense regardless. Instead of adopting them, humanity has wasted decades bickering about who is right. I despair at times!

I posted something on food security on the climate coalition website last year if you’re interested.

Send me the link

The greenhouse gas mechanism definitely does exist. Colder objects still radiate, unless they are at absolute zero. The atmosphere is well above that at 255 K or so on average, and it radiates plenty of infrared light. When that infrared light strikes the ground, what do you think happens?

. . . it doesn’t reflect to the ground at all. Virtually all of the terrestrial IR is captured by CO2. For the same reason, virtually all of the terrestrial IR that can be absorbed by CO2 is absorbed within 15m of the ground.

Not true, the atmospheric window allows IR in the 8-14 micron wavelengths to pass to outer space. What you are saying only holds true in the 4.3 and 15 micron absorption bands.

Sir, if I understand you correctly…some of the CO2 driven IR energy safely dissipates through an atmospheric window in the 8-14 micron range?

With respect to cumulative greenhouse gases, why are holes in the earths ozone no longer mentioned as threat? How did those holes repair? How did the Great Barrier reef make a recovery?

What common sense you bring to the table Daniel. ISA temperature of our world is 15C, the aim of the low carbon believers is to keep Global Warming to + 1.5 degrees ie. an increase of 10% in ISA to 17.5C. If CO2 were to cause this increase it would need to form 10% of the atmosphere, assuming it was totally opaque to heat transfer. Being heavier than air, the warming would not bother us at all, all air breathing life would be extinct from suffocation.

Sorry, can’ do arithmetic for 17.5 read 16.5…

It gets worse. 1.5C is not a 10% rise in temperature! To write about temperature in percent one must use Kelvin so 1.5C rise is only 1.5/288 = 0.5%. Can we stick with real science?

Your argument conflates infrared radiation with heat, but they are not the same thing. The phenomenon of “heat” is due to kinetic energy at the molecular level, i.e., the motion of molecules and atoms. Infrared radiation is a form of electromagnetic radiation and, although it can cause heat by causing molecules to vibrate (kinetic energy), it is not, itself, a form of heat energy.

In the specific case of heat energy, yes, the 2nd law of thermodynamics says that “heat” always “flows” from regions of higher temperature to regions of lower temperature. That is because heat energy is transmitted by molecules “bumping into” other molecules causing some of their kinetic energy to be transferred. Since the motion of the molecules is random, the energy spreads out and thus heat tends to “flow” from hotter to cooler molecules.

Electromagnetic energy is transmitted in totally different way that DOES NOT violate the 2nd law of thermodynamics. It is the ability of CO2 to “trap” infrared radiation and reflect it back to earth (not convection) that is the cause of the so-called “greenhouse effect” and therefore it does not violate the 2nd law.

Molecules bumping into one another is conduction, not radiation. It does not explain to the layman how heat supposedly radiates back to warmer surface from the cooler CO2 in the atmosphere. Just saying.

The Greenhouse warming effect of CO2 is real. But so are the cooling effects of CO2: the Co-aerosol effect and the Green effect. This is a layman explanation.

The Greenhouse effect is visible using official biospheric records over deserts with little flora. A change in CO2 leads to (precedes) a proportional change in temperature. CO2 “receives” the electromagnetic wave (at quantum frequencies) to move the orbit of electrons to an unstable and higher energy state (EM energy is converted to potential energy). At more than a billion times a second, that CO2 molecule “bumps” into another molecule at near the speed of sound. The electron returns to a more stable orbit, and the potential energy is converted to a photon that randomly emits in a direction that has a near 50% chance of going “down” vs. “up”. This delay, ever so slightly, lowers the emissivity of air (how quickly the atmosphere gives up radiative heat). The radiation that no longer shoots directly to space now lingers … maybe affecting the temperature of your skin or thermometer. If isolating this property of CO2, more CO2 begets higher temperatures.

The Co-aerosol effect is visible on an hourly scale at climate observatories (e.g., Mauna Loa). Co-aerosols are produced when natural organic sources are used to create energy. These co-aerosols, mostly invisible and odorless, reflect incoming shortwave solar radiation back to space before it is absorbed by our biosphere. If isolating this property of CO2, more CO2 begets lower temperatures.

The Green effect is visible on a monthly scale over farming areas and jungles (think Amazon). As stated in other posts, this is primarily due to the absorption of photons in the endothermic (cooling) photosynthesis process. Just like the greenhouse effect, the absorption is not totally permanent. Think exothermic (warm) decay of plant matter. But that delay change the emissivity of our atmosphere just like the greenhouse effect, but in the opposite direction. This cooling effect is so strong that temperatures have actually dropped in central Amazon. If isolating this property of CO2, more CO2 begets lower temperatures.

People that understand that anthropogenic CO2 has three effects on climate change, one that warms and two that cool, then ask a key question. Globally, which climate changing property is strongest?

That answer is fascinating. When Earth is really cold, there is little flora and few humans. So the primary effect of CO2 is to warm. When Earth is gets warm (on its way to too warm), flora and humans flourish. Our biosphere greens and cools (Google NASA Green Earth). And for those that also know that CO2 is at about a third to a half of where it needs to be and that the glacial maximum was only about 20,000 years ago, we crossed the Greenhouse vs Green effect line in approximately the 1970s. Our biosphere had finally gotten green enough to overpower the greenhouse effect and cool–partially mitigating the natural sun/sea caused 200+ year rise in global temperatures since the mini-Ice Age.

You are correct re ‘convectional cooling’, and as such means that ‘convectional heating’ is also applicable.

Seeing as CO2 have been known and proven since early 1800’s to absorb and radiate heat, your statement that greenhouse gases have no affect creates a conflict in your statement.

That is unless you can prove CO2 doesn’t do any such thing? Any kid with a couple empty bottles and a temp gauge can prove CO2 does indeed do.

But that’s the problem. The earth is not a couple of empty bottles. The earth’s atmosphere is much much more complex!

Trapped heat is not the same as the earths convection system. Anyone thinking that must have been emptying those bottles wholesale!

I strongly believe that waste heat from human activities dominates the warming, just like air conditioning a house by spending energy. About 80% of globally consumed energy enters the environment as waste heat, which cannot be ignored, from daily life (boiling water, cooking foods, air conditioning), transportation to industries.

From this point one can reasonably understand how the global warming can be linked to our activities that release waste heat. Actually it can easily simulate the temperature changes in air, land and oceans according to the waste heat allocated to them based on simple thermodynamic calculations.

Waste heat: the dominating root cause of current global warming | Environmental Systems Research | Full Text (springeropen.com)

I have never given much thought to waste heat from human activity. In fact, scientist have never really mentione it and only focused on co2,methane and deforestation.

The main focus is co2. If it were lower the waste heat would escape and no warming.

I spent time on Lake Keowee in South Carolina last month. This lake is a part of a set of reservoirs owned by Georgia Power. On Lake Keowee is a nuclear reactor, which utilizes the reservoir for cooling. Going swimming I was shocked at the warmth of the water temperature. This really made me think about heat from human activities This is not a small body of water. I can only imagine what compounding this around the world could do. Whether nuclear, coal, gas, solar or wind the amount of energy produced ends up being expelled as some form of energy that eventually turns to heat. I’m not a CO2 control believer. However, it became very apparent to me reducing usage can’t be all that bad. Reduce, reuse, recycle

The Earths historical temperature over billions of years shows very strong links between CO2 levels and ambient temperature. There is no other cause, no one had cars 350 million years ago when CO2 levels were similar and a mass extinction resulted.

Geothermal heating from 1000 centigrade magma is a major contender by conduction!

Nobody seems to discuss the small influence a relatively large increase in CO2 has on plant growth. I used to represent commercial marijuana growers. Most of them grew indoors and augmented their controlled atmosphere with CO2. Now cannabis is called weed for a reason. It grows pretty easily and is not finicky. Yet to double the plant’s yield with CO2, you need at least 3.5x increase in CO2 from ambient and, in fact, it’s more like 5x. So there’s no way this extra CO2 we are producing is just going to be gobbled up by plants.

Are you saying that the plant won’t absorb the CO2 at all unless it is increased by 3.5x or more like 5x?

Wild temperatures happen daily on the moon? Where can I get info

Magnificent! CO2 is a fake? What about endless geothermal heating and it’s energy supply, since constant motion (energy) is illegal physics

Good answer!

The best, most complete and correct answer below is from Lisa Goddard. I will simplify it even further by saying there are only two forms of heat transfer – conduction and radiation. Convection is a special case of conduction in which fluid flow (air in this case) is taken into account as a heat distribution mechanism, and influencer of heat transfer coefficients (I got an A- in my first semester of heat transfer), but ultimately it is still conduction.

Conduction occurs with the molecules or atoms of a substance come into contact and transfer energy to one another. So it is fair to say there will not be a net transfer of thermal energy (heat) from cooler air to a warmer surface through conduction.

The other mechanism of heat flow is radiation. This is the radiation of electromagnetic radiation from objects, ie the molecules and atoms in bodies. This form of energy can travel through a vacuum, such as the various forms of electromagnetic radiation that travel through the vacuum of space to our Earth. After absorbing this radiation from the sun, the earth’s surface radiates some of it back into space in the form of infrared radiation which has a little bit longer wave length than the various visible light wavelengths we see. Oxygen and Nitrogen in the air mostly ignore it, but Carbon Dioxide molecules have the geometry and composition that allows them to absorb the radiation of this wavelength. They get “excited” and re-radiate the energy, again as infrared, back out. Some goes up, and some goes back down to the surface.

So if there was only O2 and N2 in the atmosphere the infrared energy would mostly radiate back into the black body of space. But each CO2 molecule catches some and sends a portion back to earth. The more CO2 molecules there are, the more infrared radiation gets interrupted and sent back to earth, instead of out to space. That is how CO2 in the atmosphere can transfer energy to the surface, by blocking infrared energy heading to space and sending some of it back to the surface.

Overall, increasing CO2 and other greenhouse gasses reduces the earth’s ability to “cool itself off” by radiating energy into space. In other words the greenhouse gas molecules “catch” the infrared energy trying to escape earth, and “throw” some of it back to earth. Increasing greenhouse molecules, increases the amount of energy that gets caught and sent back.

In your final sentence you say that radiation increases greenhouse molecules. Energy converts to matter. That sounds faintly ridiculous. It would be useful to read an explanation of how that works.

David Watson is not saying that radiation increases greenhouse molecules. He is saying that as CO2 concentrations increase in the atmosphere due to other means (e.g., by combustion of molecules that include carbon such as petroleum, coal and wood), that more infrared radiation that would otherwise radiate out into space is being reflected back to earth. The reason is that physics of CO2 molecules allow them to be excited by radiation in infrared wavelengths where as other molecules present in our atmosphere, such as O2 and N2 do not. The energy absorbed by the CO2 when it is excited by infrared radiation causes them to vibrate and thus emit infrared radiation themselves, some of which is radiated into space, but some of which are radiated back to earth, causing the molecules of earth to vibrate (because most molecules are capable of absorbing infrared) and thus create heat. Ergo, there is a net gain of heat on earth.

It would seem that if N2 and O2 are transparent to incoming radiation that the introduction of CO2 would also act to ‘insulate’ the incoming radiation and reflect some of it back into space as well as reflect some of the exiting radiation (from the earth) back to the earth. Why don’t these effects offset?

As mentioned above, visible light coming from the sun passes the CO2 molecules without interaction. Upon reaching the ground some of the visible light is re-radiated from the ground as infra-red radiation, which does interact with CO2.

They do! That’s one of the reasons why a Greenhouse period has a more stable temperature around the planet. They leave out the global greening caused by c02 fertilization which = more oxygen = thicker atmosphere because of an over simplistic empty bottle experiment done over a hundred years ago.

A rather severe misunderstanding. When a CO2 molecule absorbs a photon of IR, it become energized. I will lose this energy by collision with another air molecule, in which case the energy shows up a kinetis energy or heat. This occurrs some billion times per second. It also can spontaneously emit a photon, returning to the ground state. In a vacuum, the life is about one second. So heat release is effectively 100%, and photon emission is a vanishingly small portion

Effectively, CO2 affects the global heat balance only in the 14-16micron wavelength range. NASA data shows that ZERO energy goes to space in this wavelength band. All else is just talk. The NASA data is at NASA Technical Memorandum 103957, Appendix E.

So why is the whole earth at a nice pleasant 80F during a Greenhouse period with co2 10 times higher then today? What you’re saying is correct but there are obviously other things going on in the atmosphere you are not aware of.

No matter what else is causing the planet to warm, CO-w, methane, and greenhouse gases are making it worse – far worse.

If I can interject into this, the other thing we are warned about is acidification of seas by co2 and that it causes north & south pole ice to melt ..

dumb question from a science dummy…. at what concentration of CO2 will ALL IR energy be trapped on earths surface and NONE be radiated into space?? at that point, will further increases in CO2 be irrelevant because there will be no more heat to trap??

At the end of the day equilibrium is between the release into our atmosphere and us consuming. THIS IS THE BEST THANK U

Read about the Second Law of Thermodynamics that heat always flows to cooler areas not hotter ones.

There are 3 ways that energy can be transferred: conduction, convection, and radiation. What John LK and Daniel H have described are 2 of those, and both are certainly at play in distributing the sun’s energy that the surface (and some atmospheric constituents) absorb. What they both have not addressed is radiation. This is how greenhouse gasses work in our atmosphere, and incidentally, how the sun’s energy reaches Earth. If there were no greenhouse gasses in the atmosphere, heat energy radiated from the surface would almost entirely radiate back to space, leaving the surface at a very very cold -18C (or about 0F, and that is averaged over the whole planet surface!). Greenhouse gasses (like CO2 and water vapor) can effectively absorb the wavelengths associated with what we call “heat”, or infrared radiation, coming from the surface or other parts of the atmosphere. They will re-radiate that energy in all directions, sending energy back to the surface, as well as out to space. This is how the surface is effectively receiving additional energy (and thus can warm). Those greenhouse gas molecules will radiate at the temperature of their immediate environment. So, CO2 or H2O near the surface radiate at a higher temperature than those same molecules higher up in the atmosphere. The altitude, above which there are no more appreciable greenhouse gasses will appear to be the radiating temperature at that point (often called outgoing long wave radiation). @Joe — in your equation below, this would be an expression for the energy balance at the surface, used to determine either the temperature of the surface or of the atmosphere, in a very idealized context, where the atmosphere is one big slab of stuff. What you are missing there though, is an ‘epsilon’ that represents the opacity of the atmosphere, basically the ability to absorb/emit radiation. The Q in that equation would be the net energy received from the sun, which is known and become approximate in the specific value for the Earth’s albedo (how much sun is reflected back to space). If you add one more equation – say the energy balance within the atmosphere, or at the top of the atmosphere, you would have enough information to solve for one, say T_surface, and find the other (T_atmosphere — though again, this would be an idealized representative temperature for the entire atmospheric column over the planet, but that is a similar situation for the surface temperature in this case too).

The intelligent and accurate retort as opposed to my less intellectual bypassing the whole argument – see previous post.

I’m after the physics describing the greenhouse effect/mechanism of heat transfer.

The equation is a radiative heat transfer equation the units are expressed in power per unit area, not energy. To get energy integrate power per unit area over time then multiply by area

The equation is for heat transfer between two surfaces, earth and the atmosphere.

Suppose the sun is delivering power to the surface over time transferring energy generating surface temperature Ts.

Q=sigma(Ts^4-Ta^4)

When is Q negative? K

In my paper I’m after the physics describing the greenhouse effect/mechanism of heat transfer.

The equation used is a radiative heat transfer equation applied between two surfaces, earth and the atmosphere. The equation has units of power not energy. For simplicity epsilon is 1.

Applying the equation to a single layer atmospheric model we know heat from the sun (Qs), and can find atmosphere temperature (Ta), earth surface temperature (Ts)……

The term “back radiation” is used to describe the heat transfer mechanism. Using the radiative heat transfer equation and applying it to a single layer model with the known values for Ts & Ta;

When is Q negative for atmosphere to surface heat transfer?

Your equation is set up to always give the answer that the atmosphere can’t warm the surface, which is wrong. You need to compare the situation with a warm atmosphere to one with no atmosphere at all.

For the present situation, Ts = 288, Ta = 255, so Q = 5.670373e-8 (288^4 – 255^4) = 150 W m^-2.

Now try Ts = 288, Ta = 2.7 K (the temperature of interstellar space). You get Q = 390 W m^-2.

In other words, with the warm atmosphere there, net radiation leaving the surface is 150 W m^-2, but without the atmosphere in the way, it would be 390 W m^-2. Input and output would no longer balance and the Earth would cool off until it was radiating as much as comes in. (This whole discussion ignores sunlight, convection, and evapotranspiration, which are necessary to give a proper balance.)

Many, many universities and others will have attempted to prove the Greenhouse Effect in a lab. However, nobody has published a single paper demonstrating heating from such a mechanism. The rewards for demonstrating the GHE are multiple Nobel Prizes for everyone involved – probably even including the president of the country. Worse still, not one publication has been seen covering failed experiments or null results. That is just dishonest surely. Null results are extremely important in science – otherwise it just becomes Groupthink.

Because it has been demonstrated so much that it is not paper worthy any more.

For instance this very article says how someone can do an experiment to show the effect themselves.

Plus you can measure the IR radiation leaving the earth with satellites.

I have done that experiment. The temperature increase was the same.

Thank you for reason and sanity

If 97 to 98% of the co2 in the atmosphere comes from natural sources how much impact can industrial sources have based on the small % of co2 in air. Isn’t it true that during the jurrasic period co2 levels were 10 times what they are today. Seems to me like a futile effort, nature rules in this case.

The atmosphere is not 2-3% artificial CO2 but 33% artificial CO2. You are confusing the fraction of emissions with the fraction of build-up. All the natural sources are matched by natural SINKS. The artificial production is not, so that’s where the increase comes from.

what are the natural Co2 ? I assume the other types are a product of burning or combustion, how do those trace gases sty up in the clouds ?-for years

It is true that CO2 concentrations in some prehistoric eras were much higher than their current levels. We believe this because of the preponderance of evidence found in the the fossil record the tells us so. (by “fossil record”, I don’t mean just actual fossils, but also other geological evidence of past climate conditions such as glacial ice cores, etc.) What the fossil record also tells us is that higher atmospheric CO2 concentrations are always associated with higher world-wide average temperatures. More importantly, it also tells us that the rate of increase of atmospheric CO2 in the current era has no precedent, i.e. it is increasing MUCH more rapidly. In the past, climate significant changes in the world wide climate occurred over extend periods of time that allowed evolutionary adaptation to occur in time to avoid catastrophic die-offs. The climate is changing far more rapidly this time around such evolutionary adaptation will not save us. What keeps me up at night is the loss of large swaths of arable land and ocean fish stock depletion.

And yet global greening grows to 7% and beyond from co2 fertilization. We need to concentrate on the 95% of the batteries filling our land fills, leaching acid into the water chain and killing the coral reefs. As this interglacial continues to warm the oceans and eventually melt the northern hemisphere like every other interglacial in the past, will release even more co2 before the next glacial period starts. Every greenhouse growers will tell you that 420 ppm co2 is a fraction for what these co2 starved plants need today. More plant growth is healthy for the planet no matter how you look at it! What should be keeping you awake at night is how close to end of life we came at a 180 ppm in 1850! 150 ppm is a threshold. 400 ppm is no scientific threshold that I know of.

In a recent study baby coral was attached to dead coral ( caused by acidity) the baby coral thrived. Explain that, but look up the experiment first.

As of 2023, the CO2 level in the atmosphere is 46% higher than the level in 1800. I’ve seen this calculated as just over 1 trillion additional tonnes of CO2 now, versus in 1800.

The “small” percentage measurement is over 2 trillion tonnes. One is a small number and the other is large. But they describe the same thing. Don’t be misled by intuition regarding the size of numbers and percentages.

yes, remove all the CO2, and all the plants die, and the human race is not far behind. you can kiss your ass goodbye if all the plants die.

No one is saying we should remove all the CO2. It’s about returning CO2 to reasonable levels.

CO2 is at the Optimal level right now

Yeah I guess if you like extra droughts and wildfires and deadlier hurricanes? Not my idea of optimal.

So we need to stop emitting CO2 right now or it will go out of optimal levels very quickly?

What is a reasonable level in ppm.?

Climate scientist James Hansen has suggested that we should try to limit CO2 to 350ppm, although for thousands of years, natural cycles didn’t bring it above 300ppm: https://climate.nasa.gov/vital-signs/carbon-dioxide/

Why 350. Cause it’s a little lower then 400?

All human civilization and agriculture developed when the CO2 level was about 280 ppmv and the (mean global annual surface) temperature was 286-287 K. Serious deviations from that either way have the potential to badly disrupt our agriculture and our civilization.

That is ridiculous. Those levels would produce Plague. Famine and War, just as they did during the Little Ice Age. Why would you want to go back to a climate that was bad for 700 years ? This mystifies me.

Agriculture is up and will continue to go up with increased co2. Decreasing co2 will lead to more starvation and more war.

…at least you see the true impetus. The entire GHE is predicated on the economic model of war mongers.

This is all nonsense. CO2 drives water vapor out of air per the Le Chateliaer Principle. H2O absorbs 7 time as much IR energy as CO2 per molecule so the temperature drops! It does not rise. This is easily demonstrated with a large bottle, baking soda and Vinegar.

So, what is your opinion of what a “reasonable level” of CO₂ is? Do you think that during the Ordovician period when the CO₂ level was at 2,240 ppm and the Earth survived that was a “reasonable level”?

Yeah, the Earth has survived a lot of things. For millions of years, the surface of the planet was molten from being struck by so many asteroids and other space debris, and the Earth survived. So I guess it’s ok to return to those conditions, too? Just because the Earth has survived hell, doesn’t necessarily mean the human species can or will. Climate change is already causing a lot of human suffering, and it could get worse if we let it — does that just not matter to you? Do the profits of fossil fuel companies matter more than human lives?

Is CFC no more depleting the ozone? Is CO2 blanketing the atmosphere at the moment?

Have you ever though considered an alternative world to fossil fuels? In 1820 86% of the entire world lived in extreme poverty, of which only 12% of the world were literate. Planes have made us less xenophobic, & civilised in a really short period of time. How would we all get around today otherwise, certainly without assembly lines? ‘Horseback’, or steam-fueled modes powered by wood, ‘all’ things powered by wood. Wood we don’t have to spare. Streets caked in manure. Meat & milk reliance. Even if due to mortality, the population was just 3 billion today, it would be a planet of ruminants, undrinkable water, and deforestation. No satellites to help us know about the Earth. Sub out that 3% Co2 we’ve added for a ‘lot’ more methane. And for the fear CO2 lives a long time, it also becomes exponentially ineffective at warming beyond saturation, as the IPCCs formula demonstrates. Doubling all the CO2 in the atmosphere today (to 800ppm) would see 0.06 degrees C of warming by 2100, according to that formula. Isn’t this purely in the hands of cloud formation and weather systems? Positive & negative feedbacks? How can it not be? How would we know if we’ve not spared the planet from global cooling if negative feedbacks had gathered momentum centuries ago? What if our CO2 prevented that from occuring? Whether water vapour is an effect or not, it’s still the major player. I find it odd in the 2000s NASA articles stated how the ozone hole had wreaked havoc with the climate & seen masses of water vapour end up in the sky. Aren’t we just trying to decide why more water is in the sky? I just don’t feel like an experiment with bottles cuts it. If the climate has never changed drastically in short periods of time before, how does adding 3% of something cause sudden extreme change? I’m aware feedback loops should exercise caution, but the Earth seems to have arrived at pretty impressive regulation systems. Maybe we just don’t understand them yet because we have about 60 years of semi-reliable data. A century ago to measure the ocean we’d pull up a bucket & pop a thermometer into it.

Survived?? 180 ppm is just Surviving. 4000 ppm grew enough food to feed dinosaurs. Dinosaurs would starve today!

John Kerry is:

Even if we get to net zero, we still need to get carbon dioxide out of the atmosphere,’ ‘This is a bigger challenge than a lot of people have really grabbed on to yet.’

Neither John Kerry or anyone else is suggesting that we eliminate all CO2 from the atmosphere (which is neither possible or desirable). If you read the quote above carefully you will note it says “net zero”, which means getting to the point where our CO2 emmissions are no longer increasing the CO2 concentration in the atmosphere. He is also warning that he thinks getting to “net zero” would insufficient to avoid the long term effects of climate change because current levels are already too high and we will therefore need to find ways to reduce the concentration to safer levels.

I thought net zero meant putting out no more than can be reabsorbed by the earth’s soils, rocks trees, oceans..with the number of people on the planet, the amount of activity, I think it will be a tall order to get to the point where there is no more Co2 being emitted..it would have to be a very basic, frugal existence. If you look at the ‘prospects’ for electric vehicles, as one example, doubts are already surfacing about how viable they are on a mass scale..

But how can we remove it from from the atmosphere yet daily industries are evolving

And what scientific reasonable co2 level would that be? 150 ppm is plant death. 420 ppm is better but still in co2 starved condition. 1500 ppm is a good level for these starved co2 plants we have today. 4000 ppm is some of earth’s strongest/healthiest times when mammals were ten times the size.

However, at concentrations above 1%, CO2 may start to affect [ 4 ]:

• Breathing rate
• Heart rhythm
• Consciousness

(or 1000ppm) https://labs.selfdecode.com/blog/carbon-dioxide-poisoning/

Plus buildings have issues with ventilation so a 1000ppm outdoor setting would have much more inside.

check your maths mate. 1% = 10 000ppm

The Earth didn’t have 9 billion people living on it when co2 was 4000 ppm. In India right now people are dying from the existing conditions because they can’t afford air conditioning or they have to work outside when the temperature is 114F with 60% humidity. For Mediterranean climates like California, Spain, Portugal, southern France, Italy and Greece a couple of degrees hotter could mean a desert. Just look across the sea. Billions of people will have to migrate to avoid death. Small countries can’t afford to have thousands of people even walking through their country. The US the richest country in the world is having trouble dealing with 3000 people a day. The war in Syria was the result of a drought causing people to lose their livelihoods and because they were a different sect than the people living within the Capital, the government decided it was cheaper and they thought easier to bomb them out of existence than to provide welfare for them. This situation caused hundreds of thousands of deaths and the largest migration in the world’s history.

Don’t just think of the plants, think of the people and other animals too.

Strive to improve, protect, serve, sufficient, prosperous, resilient, peaceful, Civil and Wild Life on Earth.

What is the rate of decay of CO2 to return to reasonable levels?

But the solution doesn’t seem reasonable at the present time.

It’s not only the plants, the Earth’s largest lungs are planctons who’ll extinct if the temp of the sea rises a bit…. That will kill the plants as well everything else, and all just because co2 rising levels

But the plants are being fed CO2 right

I am strugling to find a percentage, or range of percentages showing the proven human activity responsible for the global warming. This is a question I get stumped with by sceptics. Is there unquestionable data and science to support that, say, 70% to say 90% of the increase in temperature is proven to be a result of human activity? While CO2 modelling I appreciate is complex, does the science (at a molecular modelled level) show without question that the increase in CO2 in our atmosphere causes the associated increase in termperature we measure. While I can see the data graphs that imply this, is there detailed modelling that supports this? I am working with the IMechE to have a supportive presence at COP26 and, while I just want to clean up our planet regardless, I need good back up when I field questions from sceptics.

The obvious retort to sceptics is that many ideas essential if mainstream views are correct make sense even if climate change were a damp squib or temperatures fell e.g following a major volcanic eruption like Tambora in 1815. For that matter they work if a major food crop collapses. Typical actions include reducing waste, silviculture, regenerative agriculture, alternatives to fossil fuels (whose extraction can be polluting or destructive), fewer cash crops, combining conservation with careful use and cutting the impact per head and probably numbers of conventional livestock. These win-win options are effective no matter what. Instead the last few decades have seen huge debate on climate change rather than doing something effective to cover all bases.

All the recent warming can be attributed to human activity. If you add up all the natural forcings, the Earth should be slowly cooling. It’s only when you add the artificial ones that you get warming.

how is the temperature measured ? where do stick the thermometer ?

We can measure how much IR is coming off of the earth for starters.

There’s no good back up. Once, it was CFC depleting ozone layer. Nowadays, it’s CO2 blanketing the atmosphere. The good concept is that the entropy of the universe increases but never decreases. As the entropy increases the temperature rises. The randomness of occurances is called ENTROPY. This can be seen from the ice age glacier and interglacial zillions of years ago. The universe climate is irreversible. Therefore, heat death is a state where there’s no structure but constant temperature .

I have some question, When the sunlight hit the ground it transforms into infrared light, when the infrared light hit the CO2, shouldn’t the wavelength changed too?

My understanding is that when sunlight hits the ground, it heats the ground. Because the surface of the sun is so hot, the radiation is mainly in the visual, i.e. at relatively short wavelengths. The ground is radiating back, but because the ground is so much less hot, it radiates at longer wavelengths, i.e. in infrared. The sunlight is not transformed directly. It is the net result of absorption and emission by the ground. If CO2 is then heated by infrared radiation, and the temperature is not much different, it should re-emit the radiation in about the same wavelength.

So does Co2 absorb and emit radiation or does it block it ? The article talks about radiating, but the experiment you show seems to show blocking. Shouldn’t we see the Co2 absorb the heat and re radiate it ? Of course the experiment is faked anyway. That is a laboratory FLIR. Camera. It can show temperatures in at least 4000 colors . But the only thing it shows at all is the candle flame. Therefore the sensitivity on the expensive FLIR camera is cranked down so low it only registers if something is on fire. Then he fills the chamber with gas from a cylinder. That comes out very cold. The carbon dioxide which is cold, would have to be on fire to register on the misadjusted FLIR cam, and so effectively blocks the flame like a cold smoke screen. Then he cuts it short. I’m sorry, that is fakery to fool children.

The CO2 scatters the infrared by absorbing it and reemitting in all directions — which is exactly what the video claims to show. Since some of the infrared is bounced back to the source, it is often characterized as “blocking.”

But it doesn’t show that at all. It only shows that the cold gas blocks infrared for few seconds, to a badly adjusted FLIR camera.

Unfortunately, neither you nor I know the exact conditions of the experiment and what temperature the CO2 gas was at. However, climate scientist Jason Smerdon says that even if the gas was cold, the IR from the candle would still transmit directly to the camera if the gas were not interacting with the IR radiation. So, the experiment shows that the CO2 is scattering the IR, regardless of the gas’s temperature.

It’s also worth noting that even if there were a problem with the experiment, scientists know from many other lines of evidence that CO2 absorbs and scatters infrared energy — that fact of nature does not hinge on this one Youtube video.

Hi James, here’s a slightly experiment where cold CO2 is definitely not an issue, and it shows the same results: https://youtu.be/Rt6gLt6G5Kc?t=107 Hope this helps

How come experiments that claim to prove CO2 is a key driver of AGW use CO2 concentrations at exaggerated levels instead of the .03% to .06% we are concerned about.

I think this paper reflects a more realistic experiment . The Influence of IR Absorption and Backscatter Radiation from CO2 on Air Temperature during Heating in a Simulated Earth/Atmosphere Experiment: uhttps://www.scirp.org/journal/paperinformation.aspx?paperid=99608

If Mars is 95%co2 how come it is not hotter. My last question is what happened to the sunspots. Did the industrial revolution cause that too?

Most of Earth’s greenhouse effect comes from water vapor and clouds, which together account for about 25 K of the Earth’s 33 K difference from the radiative equilibrium temperature (CO2 accounts for most of the rest). Mars has a very dry atmosphere. In addition, its atmospheric pressure is very low, so the absorption lines are not pressure-broadened the way they are on Earth, and the greenhouse effect is less effective. Lastly, Mars receives much less sunlight than Earth. Despite all this, Mars does wind up with a greenhouse effect of about 4 K (radiative equilibrium temperature is 210, emission temperature is 214).

Because Mars is further away from the sun and has less atmosphere to keep the temperature in.

If CO2 is not responsible for temperature increases why is Venus hotter then Mercury?

Indeed the climate is changing and CO2 certainly seems to be playing a role. However, I find the statement “Unfortunately, we don’t have thousands of years to wait for nature to absorb the flood of CO2. By then, billions of people would have suffered and died from the impacts of climate change; there would be mass extinctions, and our beautiful planet would become unrecognizable” to be coming out of thin air. The climate has changed in human history (medieval warm period, ice ages) and humans have always been able to adapt. Why would this climate change be different? “Billions dead” ? Why?

Droughts, wildfires, extreme heat, hurricanes, sea level rise, infectious disease — climate change makes all of these things worse, and the climate is changing faster and more dramatically than in all of human history. Surely we can and will adapt, and a big part of adapting means moving away from fossil fuels.

Recently, I became embroiled in an online debate on the subject of anthropogenic global warming (“Claim”) originated by a talk radio host, who was hostile to the claim of anthropogenic global warming. Some responders were outright abusive, but one at least posed the following counter-arguments to the Claim:

(1) “So one of you educated climate alarmists please the explanation of how CO2 in the atmosphere is capable of increasing its fingerprint absorption wavelengths of 2.7, 4.3, and 15 microns so that it can absorb more than 8% of the infrared spectrum that it already does” “Don’t give me the ‘broadens its wings’ explanation b/c that only accounts for about 1.7% increase when the CO2 is doubled” (explanation offered by the IPCC)

“Since the science is ‘settled’, you no doubt have that explanation handy and it will no doubt be in peer reviewed form”.

(2) “Explain while the dilution of the CO2 molecules by other molecules is ignored. Every CO@ molecule in the atmosphere is, at current concentration, surrounded by 2500 other molecules. In order for CO2 to heat the atmosphere to just one degree, the CO2 molecule would have to start at a temperature of 2500 degrees C.

(3) “Also, explain why the climate scientists use the Stefan-Boltzmann constant incorrectly to explain radiation from the air to the ground. (The) Stefan-Boltzmann constant is how much radiation is given off an OPAQUE surface at a given temperature.”

This was actually the least contentious response. I was just wondering how anyone at Columbia would answer these counter-arguments.

https://news.climate.columbia.edu/2021/02/25/carbon-dioxide-cause-global-warming/

I did read the article, which was very informative. I was informed by someone else that the Stefan-Boltzmann constant is not used in the more current, detailed models, which accounts for “Challenge” 3. Challenge 2 seems a bit absurd, and is a thermal transfer issue. The one that kind of confounded me was Challenge 1, an atmospheric chemistry issue. Would have something specific to say about this one, say if it was posed directly to you?

1) A quick thought experiment.

Average moon temperature 133.15K (quick guess based on google searching)

Average earth temperature 293.15K (Another guess based on a guess of 20C average)

160K difference due the greenhouse effect.

1.7% of that works out at 3 degrees of warming

You forgot to mention the earth is bigger and has a liquid metal core.

I would like to know what is the way that carbon dioxide involves global warming

If you see the earth as a ball receiving energy (from the sun) and emitting energy (infrared due to the earth’s temp), you may understand that in the long run , incoming and outgoing energies must be equal.exept for storage changes. So all outgoing energy is infrared. From infrared spectroscopy we know some gases absorb infrared energy in the infrared area. CO2 is one of them as is H2O vapour. Gasses like CO2 do not only absorb infrared radiation, but they also re-emit the same radiation, , this time in whathever direction, partly back to the earth. If you would measure the infrared output of the earth at sealevel and you would measure this outside the atmosphere, you would find a difference. in certain bands, much less infrared energy leaves the earth. If this energy does not leave the earth, it can only heat it. Wenn the temperature of the earth rises a little bit, the earth starts emitting more infrared energy, so balancing again, at a sligtly higher temp.

Hi I was wondering how does carbon dioxide have a big impact on global warming. I was just wondering for a school project.

Be sure: You will not get an answer here.

I find many of these answers far too simplistic and not nearly quantitative enough to satisfy my curiosity.

I note that the insulation response involves elements of convective resistance, conductive resistance and radiative resistance. In all cases it is a logarithmic function and not linear. Why no mention of any of these factors when it comes to CO2? Doesnt each doubling of CO2 halve its already minuscule IR absorption factor? If so shouldn’t you point this out so your followers are not unduly alarmed

I also note that the hottest areas on Earth are found in dry, below-sea-level valleys located in temperate zones. This correlation appears to have nothing to do with CO2 concentrations. The hottest official temperature that ever occurred on Earth occurred at Greenland Ranch in Death Valley in 1913 long before the heavy use of fossil fuels were in effect. How can this be? Are we cherry picking only the factoids that support our preferred premise?

My own idea is that moist air carries far more thermal inertia than dry air and yet the two are treated identically by using simple average temperature. Aren’t joules/mass the appropriate metric for the effect of heat trapping gases?

Further, how far must IR radiation travel before encountering a CO2 molecule that absorbs its energy at .04% concentration at standard temperature and pressure? Once absorbed doesn’t this energy lead to convective forces carrying the molecule into lower pressure zones at higher altitude before losing its energy to other cooler molecules. There are endless complexities to these energy transfers that I have never heard explained satisfactorily, other than with the typical simple bromides.

Moreover, more CO2 can’t simply mean increased oceanic evaporation because if that were true there would be runaway evaporation causing more greenhouse gases until the oceans boiled away. Clearly there can be no positive feedback associated with increased evaporation. I might suggest that cloud cover of all types have a great deal of influence over regulating radiation flux impinging on the surface. No mention of any of this – why?

Lastly your spectrum of greenhouse radiation chart (above) makes no mention whatsoever of water vapor with its broad spectrum of IR radiation absorption making it the only significant greenhouse gas and often completely masking the effects of any additional CO2 interference

If I understand you correctly, you want to adress 3 points.

What is the quantative relation between absorbtion and concentration for CO2? Such issues are very well known in standard Chemical analysis, Any good chemistry book on spectroscopy can help you further.

The relation between amount of water vapour in the air and temperature. You state correctly that dry area’s have the highest temperatures. This is very well known in all desert area;s around the world. However, only at daytime, the nights are cold. In general, very unevenly distributed water vapour levels, both by region as by height, makes understanding and calculating very difficult. CO2 levels, which are, contrarely to water, evenly distributed around the world, have virtually no influence on local temp. differences.

Your third point: ,”” more CO2 can’t simply mean increased oceanic evaporation”” is incorrect. CO2 has an independent (its own) contribution to earths temperature and thus to oceanic evaporation.An associated positive feedback can be a moderate one, it does not automatically mean an explosive one.

Thanks for affirming my point that measuring the actual heat retaining characteristics of our complex atmosphere is difficult. I have always suspected as much.

Can you address another question I have regarding the IR heat trapping capabilities of atmospheric CO2. I have a very image oriented mind and here is the image I conjure up regarding the phenomenon.

Sol generated photons of some arbitrary wavelength eventually pierce the atmosphere to strike (interact) with atoms/molecules of the Earth’s surface thereby raising their energy level. These atoms/molecules in turn transfer their excess energy by conduction/radiation to adjacent particles who which selectively lose energy by emitting photons of a wavelength that CO2 molecules can catch. Since the solid angle of these emitted photons will occur in any random x,y,z coordinate, only 50% should be “sky bound” Correct?

At some point CO2 does its job of catching a sky traveling photon only to re-emit it at another random solid angle. Presumably half of all these photons will emerge in the hemisphere headed back towards the solid Earth, the other half will continue in some random skybound direction. To my simple way of thinking the net effect of these interactions is zero

Where have I gone wrong in my thinking ?

The planet Mars has an atmosphere of 96% CO2 but a surface temperature of -62°C (-80°F) shouldn’t the planet be a bit warmer than this if CO2 traps heat even allowing for the thinner atmosphere and a further distance from the Sun that the Earth?

I just want the temperature to be 70 degrees F constantly, worldwide, how would I go about accomplishing that?

Impossible. Suppose, it was 70 degrees worldwide, so emitting roughly equal amounts of IR radiation per square meter everywhere, where would that energy come from ?, the sun?, no way. Impossible.

Why are most, if not all, of the UN’s IPCC temperature models over the past 20 years showing temperature increases much, much higher than what has actually happened? And that’s even with RSS temperature models cooling the past and warming the present more and more with every new model version? If the IPCC’s models can’t have at least an average error over and under actual temperatures, measured by a obviously biased-to-warmth RSS model set, then how can we ever believe the CO2 alarmist’s calls to action on climate change?

All the models fail because only parameterizations instead of established meteorological equations. Plus, since none of them can replicate past climates — they can’t predict the future. However, I have found some proof of human-caused climate change … https://www.youtube.com/watch?v=2BPsloM04R0

How Exactly Does Carbon Dioxide Cause Global Warming? BY SARAH FECHT |FEBRUARY 25, 2021

The article notes that ‘ Water is indeed a greenhouse gas ( and ) it absorbs and re-emits infrared radiation, and thus makes the planet warmer .’ The article also notes that ‘ warmer air holds more water’ This appears to suggest an uncontrolled feedback loop where warmer air holds more water in turn making the planet warmer. The article also notes that ‘ temperature determines how much moisture can actually be held by the atmosphere .’ Again suggesting the possibility of an uncontrolled feedback loop. Although most water drops out of the atmosphere as rain there is still significant volumes of water in air across the globe where the temperature is above the dew point. These natural volumes of water in air appear to be significantly in excess of the volumes of CO2. Indeed the volumes of water being injected into the upper atmosphere by aviation contrails have had the effect of increasing the level of atmospheric water through a mechanism that has not existed in the past. Given that both CO2 and H2O are greenhouse gases the article does not seem to address how we can measure the relative influence of the two gasses.

The article addresses this issue. We can lower the amount of water in the atmosphere by lowering the temperature. We can lower the temperature by reducing carbon emissions.

Thank you for the prompt response and appreciate your feedback that we can  lower the temperature by reducing carbon emissions.   Given the clear evidence of global warming what is the scientific explanation for the way in which carbon emissions absorb more sunlight than water vapour.  

I Think water vapour absorbs more, but 2 aspects might be considered.

• water vapour can build clouds, reflecting sunlight so lowering energy input. a negative contribution.
• CO2 is roughly evenly distributed around the world and relative to height, water vapour is not. Think of an extreme experiment in your mind. If all water vapour was concentrated in a narrow vertical cilinder and zero elsewhere, what would happen? Distribution matters.

Sorry but I keep hearing this..H20 or water is a gas ?? it’s water !

The author seems to have forgotten that plants take up CO2. There will be better plant growth with more CO2. Insufficient CO2 will make a block to plant growth. There are more people on the planet, surely we need more plants to grow more food?

The author of this comment seems to have not read through to the end of the piece.

I want to propose a different perspective on the way we should looking. Look only to energy in and energy out at the very outside of the worlds atmosfere.

Use minds experiment. Use a world with a normal airshield, but without CO2. We use long term stable temp., incoming energy (sun) and outgoing, let’s say at a 50 miles border outside the world( IR radiation), must be equal.

Now we add CO2. From spectroscopic data we read that outgoing energy is far less in the CO2 absorbtion window.

https://www.physi.uni-heidelberg.de/~eisele/schuelerlabor/SpektroskopieUmweltphysikExperimente.pdf

We started with incoming and outgoiing energies are equal in stable temp. conditions. As the sun is still the same and less energy is emitted in the greenhouse absorbtion bands, the temp starts raising untill the emitted IR once again , aquals thes sun’s

The earth can be considered what in physics is a black radiator. Its behavior can easily be calculated using a formula.

The rising temp. of the earth leads to more IR radiation, outside the greenhouse windows, leaving us forever. Now we have a stable and equal situation again, The energy not leaving the earth in the greenhouse windows equals the energy difference between the 2 black radiators is thus easily calculable.

A simplified way of calculating is: 1/ the energy blocked in the greenhouse gas window is expressed as a percentage of total IR radiation. example 5% 2/ the extra IR energy emitted by the black radiator (the earth) per degree temp raise is expressed in percentage of total IR emitted, example 2%. Now the earths temp. raise is 2.5 %

sorry, 2.5 degrees of course

In the climate discussion the fate of excited CO2 molecules in the earth’s atmosphere has been ignored. The amount of CO2 in the atmosphere is widely believed to be responsible for global warming due to human activity. The IPCC explains the greenhouse effect in the atmosphere in their frequently asked questions as follows: “Much of the thermal radiation emitted by the land and ocean is absorbed by the atmosphere, including clouds, and re-radiated back to Earth. This is called the greenhouse effect.” The mentioned greenhouse effect of CO2 is not in accordance with the molecular properties of CO2. These have to be treated quantum mechanically. The interaction with radiation as well as intermolecular interactions are described by quantum mechanics. There are selection rules for possible energy transtions in molecules. Vibrational transitions are limited to molecules whose electric dipole varies during the vibration. This exclude homonuclear diatomic molecules such as O2 and N2 . For rotational transitions, the molecule must have a permanent electric dipole. This excludes homonuclear diatomics, with the exception of O2 which has a triplet electronic ground state allowing magnetic dipole rotational transitions. Therefore O2 is important in cooling the earth by emitting radiation from rotational states. The radiative lifetime and collisional deactivation of vibrationally excited CO2 have important consequences for its ability to emit infrared radiation under atmospheric conditions. CO2 in its vibrational ground state may be excited to its vibrational excited state CO2 (0110) by radiation with wavenumber 667.4 cm-1.This is the strongest infrared absorption of CO2 and therefore the main process for excitation of CO2 by infrared radiation from the earth’s surface. The vibrationally excited state CO2 (0110) emits radiation with a rate constant kr = 2.98 s -1 This state may be deactivated in bimolecular collisions with CO2 and N2 in their vibrational ground state. The deactivation rate may be calculated using data from J. A. Blauer and G.R. Nickerson, A survey of vibrational relaxation rate data for processes important to C02-N2-H20 infrared plume radiation. Prepared for Air Force Rocket Propulsion Laboratory, October 1973, Distributed by National Technical Information Service, US Department of Commerce, 5285 Port Royal Road, Springfield VA. 22151. The rate constant for bimolecular deactivation by ground state CO2 or N2 depends on temperature T. For instance in the case 200 ppmv of CO2 in the air the rate of deactivation by collission with N2 amounts to 6.8 x 1014 s-1 at 288 K at ground level and to 5.5 x 1010 s-1 at 198.5 K and 80 km and above sea level. This means that as soon as a CO2 molecule gets excited by absorption of surface IR radiation to the state CO2 (0110) it has a negligible chance of emitting a photon. Therefore the entire observed 667.4 cm-1 radiation from the atmosphere must arise from the Boltzmann population of the state CO2 (0110). This holds even if the CO2 concentration is doubled. Therefore the statement of the IPCC concerning back radiation is untenable. Any observed 667 cm-1 radiation in the atmosphere originates from the sun, directly or through Raleigh scattering by CO2 in the upper atmosphere.

Oef, quite a bit, if I understand you correctly, You think CO2 molecules remain in their excited state for a longer time, making them inactive for further action. Not from theory, but from real measurements, we know that in the CO2 window, the IR emitted at sealevel is far larger than outside the atmosphere, proving there is constant absorbtion. How do you explain this.?

Dear harrie geenen, Note that one day after I posted my comment, I saw that there were serious typographical errors in the representation. I submitted a revised version with a different notation of powers of ten. Please adhere to the new version.

The particular excited vibrational state of CO2 has a radiative lifetime of 1/kr = 336 ms. That would be the lifetime under collision free conditions. However under atmospheric conditions the excited molecule suffers many collisions during that period which convert the excitation energy into translational and rotational energy of the collision partners.

Denote the rate constants for quenching the 667.4 cm-1 emission by collisions with CO2 or N2 respectively by k1(T) and k2(T). The concentrations of CO2 is denoted as Ω(CO2). It is given by Ω(CO2) = FC * (DA / MA) [mol / m^3] where the molar mass of air MA = 0,289644 kg / mol. DA is the local density of air, FC is the fraction of CO2 in air.

The quantum yield Φ(T) for emission of radiation by CO2 (0110) at temperature T is given by Φ(T) = kr / { kr + k1(T) + k2(T) }.

Denote the number density in the Boltzmann population of the excited state CO2(01^10).for the given temperature and fraction of CO2 by N(BEC,T). It is given by

N(BEC,T) = A x Ω(CO2) x exp{-667.4 / (kB x T)}

where A is Avogadro’s constant, kB is Boltzmann’s constant. Their values are A = 6,022 x 10^23 and kB = 0.6952 cm^-1 / K.

The number of photons NP emitted per second by CO2(01^1 0) is given by

NP(T) = Φ(T) x N(BEC,T) x kr / s

With the energy EP of a photon at 667.4 cm^-1 = 1325.4 x 10^-23 J, the amount of energy E(667 cm-1 ) radiated per second from 1 m3 air is given by

E(667 cm-1 ) = NP(T) * EP [J /s]

The values of E(667 cm-1 ) obtained in this manner in the case of 200 ppmv are: 1.56 x 10^-11 J /(s m^3) at 288 K and 0 km above ground and 6.51 x 10^-12 J /(s m^3) at 198.5 K and 80 km above ground.

Clearly more energy is radiated at ground level. The basic reasons are that both the thermal energy kB x T and the density of air larger.

With regard to the satellite measurements, I wonder what the technical details are. Such as the exact radiation frequency and bandwidth selected for detection and how an intensity profile as a function of height above ground is extracted from the total energy measured.

Although CO2 does not reemit radiation, its effect on radiative transfer is evident above 60 km height. There it contributes to absorption and scattering of direct solar radiation on its path to the earth’s surface. At heights above 40 km interaction of high energy solar particles can lead to destruction of CO2. Capture of electrons emitted from the sun may produce the anion CO2−.Reaction of CO2 with solvated electrons in water droplets will also produce the anion CO2−. Photoionization of CO2 yields the cation CO2+. Excitation by 150 -210 nm radiation leads to photodissociation of CO2. These photo products of CO2 can react further with other intact components of air or their photo products. For instance the anion CO2− reacts with H2O yielding hydrocarbonate and formate anions. At 50 km height with 400 ppm CO2 and 25000 ppm H2O, the collision rate between CO2 and H2O molecules is calculated to be 6.14 x 10^33 / (s m^3) . Prior to electron autodetachment the anion CO2− has a lifetime of 30-60 μs. During its lifetime there are many collisions with H2O to cause reaction. The processes mentioned above initiated by solar radiation decrease the concentration CO2 at heights above say 40 km, resulting in both more 667 cm-1 solar radiation reaching ground level and less Raleigh scattering of it into space.

Finally, I want to stress the importance of radiation from rotational states of O2 in cooling the planet. A result of burning materials is the consumption of O2. Photosynthesis in plants, bacteria and algae repair the damage by producing O2 from CO2. This may not fully refill the loss of O2 as forests are destroyed. It would be helpful to find if the concentration O2 in the atmosphere is affected by human actions.

Unfortunately superscripts and subscripts were ignored in the representation of my comment 2053342. Therefore I modified the text to indicate superscripts with the symbol ^. Powers of 10 are now represented as 10^. 6.8 x 1014 s-1 had to be 6.8 x 10^14 / s and 5.5 x 1010 s-1 had to be 5.5 x 10^10 / s. The revised version of the comment appears below. In the climate discussion the fate of excited CO2 molecules in the earth’s atmosphere has been ignored. The amount of CO2 in the atmosphere is widely believed to be responsible for global warming due to human activity. The IPCC explains the greenhouse effect in the atmosphere in their frequently asked questions as follows: “Much of the thermal radiation emitted by the land and ocean is absorbed by the atmosphere, including clouds, and re-radiated back to Earth. This is called the greenhouse effect.” The mentioned greenhouse effect of CO2 is not in accordance with the molecular properties of CO2. These have to be treated quantum mechanically. The interaction with radiation as well as intermolecular interactions are described by quantum mechanics. There are selection rules for possible energy transtions in molecules. Vibrational transitions are limited to molecules whose electric dipole varies during the vibration. This exclude homonuclear diatomic molecules such as O2 and N2 . For rotational transitions, the molecule must have a permanent electric dipole. This excludes homonuclear diatomics, with the exception of O2 which has a triplet electronic ground state allowing magnetic dipole rotational transitions. Therefore O2 is important in cooling the earth by emitting radiation from rotational states. The radiative lifetime and collisional deactivation of vibrationally excited CO2 have important consequences for its ability to emit infrared radiation under atmospheric conditions. CO2 in its vibrational ground state may be excited to its vibrational excited state CO2 (01^10) by radiation with wavenumber 667.4 cm-1.This is the strongest infrared absorption of CO2 and therefore the main process for excitation of CO2 by infrared radiation from the earth’s surface. The vibrationally excited state CO2 (01^10) emits radiation with a rate constant kr = 2.98 / s. This state may be deactivated in bimolecular collisions with CO2 and N2 in their vibrational ground state. The deactivation rate may be calculated using data from J. A. Blauer and G.R. Nickerson, A survey of vibrational relaxation rate data for processes important to C02-N2-H20 infrared plume radiation. Prepared for Air Force Rocket Propulsion Laboratory, October 1973, Distributed by National Technical Information Service, US Department of Commerce, 5285 Port Royal Road, Springfield VA. 22151. The rate constant for bimolecular deactivation by ground state CO2 or N2 depends on temperature T. For instance in the case 200 ppmv of CO2 in the air the rate of deactivation by collission with N2 amounts to 6.8 x 10^14 / s at 288 K at ground level and to 5.5 x 10^10 / s at 198.5 K and 80 km and above sea level. This means that as soon as a CO2 molecule gets excited by absorption of surface IR radiation to the state CO2 (0110) it has a negligible chance of emitting a photon. Therefore the entire observed 667.4 cm-1 radiation from the atmosphere must arise from the Boltzmann population of the state CO2 (0110). This holds even if the CO2 concentration is doubled. Therefore the statement of the IPCC concerning back radiation is untenable. Any observed 667 cm-1 radiation in the atmosphere originates from the sun, directly or through Raleigh scattering by CO2 in the upper atmosphere.

I hope we can agree on the fact that in the CO2 window, there is a constant strong absorbtion of the infrared radiation originating from the earth. There are 2 possibilities to release this energy again, 1, by emitting IR radiation, what the IPCC sees as dominant, in any direction, partly into space, partly back to earth. In reality, not a single action, but many absorbtions and re-emittings.

2, what I think you are meaning, by colliding to other molecules. In this case the greenhouse effect would be larger. In the radiation option, a part is kept here and a part goes in space and is lost. In loosing energy through collisions, all energy remains here and the greenhouse effect would be a lot stronger.

In principle both effects could be working but there would be a difference in the thermal gradient from the earth to the outside off our air layer.

By measuring this gradient, one can calculate the relative contributions.

If there would be no other greenhouse gasses, outher CO2, and all absorbed IR radiation would be transferred into heat (collisions), we would have an inverse thermal gradient, so hottest high in air and cooler closer to earth.

harrie, I do not agree with your statement that in the CO2 window, there is a constant strong absorbtion of the infrared radiation originating from the earth. The earth is not a black body. The materials of which the earth surface consists are not homogeneously distributed. Different constituents have different emission spectra. Therefore you have to distinguish were the observations are made. Above sea or above forests or above desserts? With regard to CO2 we may restrict the discussion to vibrational and rotational transitions. Vibrational transitions are in the infrared and rotational transitions in the microwave region of the electromagnetic spectrum. Energies within molecules are quantized. That means that only radiation with specific frequencies are absorbed or emitted. The probability for absorption or spontaneous emission at such frequencies depends on the magnitude of the corresponding transition moments. The important question is which constituents of the earth surface emit radiation at the specific frequencies required for these transitions in CO2 at the actual surface temperature. I did not came across the relevant data. One thing is certain, transfer of energy from the earth surface to molecules is possible without involvement of radiation, namely when they collide with the surface. The thermal gradient in the atmosphere is a consequence of the gradual reduction in pressure as the height increases, arising from the action of gravity. At constant volume the temperature drops according to the ideal gas law: P V = n R T with n the amount of substance and R the gas constant. The temperature gradient has nothing to do with global warming due to human activity.

The experiment with a bottle full of CO2 vs normal air is not a comparable experiment to prove the hypothesis of the earths warming as the hypothesis is 0.035% vs 0.04% creating a 2 degree increase is the issue, so the experiment would be to have a comparable increased amount of CO2 in one bottle vs the baseline and to see if there is a 1-2 degree increase in temperature in the CO2 bottle vs the baseline bottle. if there is, then the hypothesis would be proved. Note the light source would need to be turned on and off every 12 hours and assumes the sun gives off a constant radiation over a 12 hour period, which I was not aware it did given the elliptical oscelating orbit.

increased emissions of CO suppress the oxidative capacity or power of the atmosphere which leads to more CO2 and stronger greenhouse effect. Many blame Co2 as the main cause of global warming while the CO is actual problem and prevents CO2 from functioning naturaly. Am I correct?

So if CO2 reflects infrared radiation coming from earth, wouldn’t it also reflect radiation from the sun back into space?

Yes, but it reflects back far more infrared than it does visible light. So the visible light can reach the earth and turn to heat. Part of the heat which would previously escape as infrared is now trapped.

what is the average distance an infrared photon travels before encountering a CO2 molecule at 400 ppm and STP?

As water vapor concentration is roughly 100 times bigger than CO2 and it also traps infrared light .Why it is ignored ?

Isn’t “ambient air only 0.004 % CO2? Then how can a “hollow tube filled with CO2” be valld test? Why don’t they use ambient air and try the same experiment?

You stated “Before humans began burning fossil fuels, naturally occurring greenhouse gases helped to make Earth’s climate habitable. Without them, the planet’s average temperature would be below freezing. So we know that even very low, natural levels of carbon dioxide and other greenhouse gases can make a huge difference in Earth’s climate.” Haven’t you ignored the large effect of water vapor when you conclude that “even very low” CO2 and “other greenhouse gases can make a huge difference” Didn’t you just incorrectly imply that water vapor percentage is “very low” by not mentioning it or its effect is minimal? Neither is true are they?

The runaway Greenhouse effect on Venus is not real. It goes as follows: During the cosmic bombardment; when the planets were molten rock, Venus and Earth received water through millions of meteorites that were constantly crashing into the planets. On Venus, being much closer to the sun, water never got the chance to condensate to water. So all the water received, built up as vapor from the start. The pressure kept increasing while it received more water until the level we see today. It never got a chance to form oceans and rivers. The energy that Earth receives from the sun is less so oceans could form. With the energy that Earth receives from the sun it is a physical impossibility to trigger a runaway greenhouse effect like on Venus. Whatever we do, even if we burn every last grain of coal and drop of oil, we will never completely destroy earths life sustaining climate. All fossil fuels come from a vibrant earth full of life, if we recycle all that dead carbon back into the atmosphere and into new life, the total biomass on earth will be similar than that of the time all fossil fuels formed; millions of years ago.

i didn’t read the whole paper, but the response was unresponsive re: co2. the response referred to many or all greenhouse gases, and didn’t address CO2 contribution solely.

Ha! I wonder who came here solely because of online school.

A better experiment would be to have 3 large containers – one containing earth’s atmosphere with no CO2, one with atmosphere of 0.025% CO2 and one with atmosphere of 0.04% CO2 (present level). Apply exactly equal heat to all 3 containers in a controlled environment for the same length of time. Then see how much more or less heat each container retains over a period of time.

im new to this global warming and climate change and i was looking for how much the earth temperature increases for the past 150 years (from 1850-2000). i have no idea about this 0.177±0.052°c. what does the temperature in the left and right is for? thank you so much.

I’m not sure where you found that. Every climate center in the world has different growth rates since 1850. They all hover around 1.7 degrees C for the time period in questions. You can easily download their data by searching for Global Temperature History … followed by the site: NOAA, NASA, Berkeley Earth, UK Met Center, Cowtan-Way, Japan Meteorological Organization.

Excellent science. But the title is misleading. The title makes the assumption that CO2 only has one climate-change property–Greenhouse. Let’s be specific.

CO2 has three climate change properties that are well documented. Co-Aerosol that cools the planet from aerosols associated with anthropogenic CO2. And Green, the huge effect that CO2 is having on type C3 flora that cools Earth. So one warming property and two cooling properties.

The way to discover the “full” effect of CO2 is to look at the past 60+ years of real-time CO2 cause-effects on global temperature and the results are quite clear. The highest annual increases seen in CO2 precede global cooling. The lowest increases seen in CO2 annual increase precede explosive global warming. Please do this simple analysis with any of the full set of records from: NASA, NOAA, MLO, Berkeley Earth, Met Center, Cowtan-Way, Japan Meteorological Organization, RSS, or UAH.

Looking at any long-term lag (more than three months, the time it takes CO2’s Green property to create life that cools) proves this point. All of the above highest authorities in climate science concur. There is no higher authority than actual climate data.

Good science. Great explanation of the greenhouse property. But misleading because of factual omissions.

The title should be, “How Exactly Does Carbon Dioxide’s Greenhouse Property Warm the Atmosphere”. And then at the end, note that anthropogenic CO2 has two properties that cool. And that the full effect of CO2 is to cool Earth. The co-aerosol effect is currently neutralizing the Greenhouse effect in the short-term. The Green effect overpowers the Greenhouse effect after three months and is lasting.

one thing that bothers me after reading the scientific facts on the warming effects of CO2 is that the heat absorbed by the greenhouse gas seems to be radiated from the earths surface, and following this trend I would say that the action seems to be secondary, after the suns light is absorbed at the surface. Would it not be more accurate to say that the denuding of millions of hectares with deforestation, would be the initial cause of the source of the heat, especially as trees absorb CO2, and many studies claim the shade caused by the canopy is between 10 and 20C cooler, this cool air blanket being removed would be as much if not more of a cause of g;global warming than the CO2 by itself?

Photosynthesis is endotermic reaction and good adsorber of extra energy. If energy is not going in to the plants, it s heating up land and atmosphere.

What you write in the end is basically Urban Heat Island effect.

willl we eventually run out of air to breathe?

No, earth is getting greener due higher CO2 and temperature. Earth is still below optimal CO2 consentration for plant growth. In Photosynthesis basically each CO2 molecule will produce equal amount of O2. “T oday’s concentration of oxygen could be produced by  photosynthetic  organisms in 2,000 years” says Dole, M. (1965).  “The Natural History of Oxygen” .  The Journal of General Physiology

Firstly, Co2 is heavier than air. how does it stay in the upper atmosphere ? Since it’s a trace gas, where do these images we see, come from? there is the train of thought that increases in Co2 do not lead to corresponding increases in temperature. how is the Earth’s tempereature measured ?

Can we agree Co2 has helped green the planet ? more crops more trees, more grass. healthier soil

Yes. Nasa tells “ The Earth has become five percent greener in 20 years. In total, the increase in leaf area over the past two decades corresponds to an area as large as the Amazon rainforests”.

That’s interesting..so if most of the world moves to Net Zero…that could be less good for all plants, crops. that would require more fertiliser, chemicals etc. Funny how this was not mentioned at Cop26 nor the effect of world population increase

It is said that without greenhouse gasses average temperature of earth would be abouf 32K colder. It is also said that DOUBLING of CO2 will cause 1,5 to 4,5 K warming. This should also apply for slitting the amount of GHC in atmosphere.

We can calculate that from single CO2 atom we have doubled CO2 about 137 times. Justsplit molecular weight of CO2 by Avogardo number to get weight of CO2 and then start to double it. After 137 doubling you will get about then amount of CO2 in atmosphere.

So if CO2 would be ONLY GHC shoudn’t each doubling increase temperature by 32K/137? And because water has effect too, GHC effect is much smaller?

The sun shines light upon the earth, both visible and infrared. The earth radiates almost all energy back into space as infrared. Some of the infrared is absorbed by CO2 and other gases. These gases absorb certain wavelengths while allowing others to be transmitted. What is the relationship between the density of these gases and transmission through the atmosphere? It seems to me that transmission through miles of atmosphere would be completely blocked once any level of gas was present and the addition of more gas would make no difference.

Part of the problem is the 24/7 society we live in..at any time someone is driving, flying, using electricity, buying a product, making meals…being born ! so Net Zero targets are harder to acheive now than in the pre industrial age..even with new technology

I chose this link because of a comment made regarding the use of carbon dioxide as a refrigerant, alleging that this fact makes climate change due to gasses like CO2 highly unlikely. A couple of websites explain how CO2 works as a refrigerant, which I only read enough to grasp imperfectly and came looking for more. Since the person who made the assertion that drove me here has, in the past, expressed ideas that, while couched in seemingly articulate terms, strike me occasionally as patent conservative gobbledegook. Being too polite to immediately call him out on his altered state, wishing to afford him the benefit of the doubt, I re*trained myself. It seems to me that what he proposes might do well being included in discussions like this to insure greater understanding of this horrendously significant natural phenomenon.

CO2 is used as a refrigerant because the CFC / HCFC / HFC refrigerants are problematic for the ozone layer. CO2 is not.

You’ll note that they don’t use, for an example, monoatomics as a refrigerant. Why? Because the amount of energy an atom or molecule can transit from one place to another (its specific heat capacity and latent heat capacity) is dependent upon the DOF (Degrees of Freedom) of that atom or molecule.

No, they use complex CFC, HCFC or HFC molecules with many DOF.

By the same token, they don’t use complex high-DOF molecules as a filler gas in dual-pane windows… they use low-DOF monoatomics. Why? Because the low Degrees of Freedom transit less energy from one window pane to the other. If CO2 was such a terrific ‘heat trapping’ gas, it’d be used as a filler gas in dual pane windows. It’s not.

CO2 is similar, it is a high-DOF molecule which can transit quite a bit of energy, especially if compressed to the point that it undergoes phase change. It requires higher pressure than the CFC, HCFC or HFC molecules, but that’s a tradeoff that’s apparently acceptable.

It is the monoatomics (Ar) and homonuclear diatomics (N2, O2) which are the actual ‘greenhouse’ gases. Remember that an actual greenhouse works by hindering convection .

In an atmosphere consisting of solely monoatomics and homonuclear diatomics, the atoms / molecules could pick up energy via conduction by contacting the surface, just as the polyatomics do; they could convect just as the polyatomics do… but once in the upper atmosphere, they could not as effectively radiatively emit that energy, the upper atmosphere would warm, lending less buoyancy to convecting air, thus hindering convection… and that’s how an actual greenhouse works, by hindering convection .

We can see this in the dry and humid adiabatic lapse rate. Remember that the lapse rate is ‘anchored’ at TOA (Top of Atmosphere… that altitude where air density reduces sufficient that the atmosphere is no longer opaque to any given wavelength of radiation).

Water vapor reduces the lapse rate (~9.81 K km-1 dry ALR; ~3.5 – ~6.5 humid ALR) by transiting more energy from surface to upper atmosphere, which has the effect of attempting to reduce temperature differential with altitude (ie: the lapse rate reduces), while at the same time it radiatively cools the upper troposphere faster than it can convectively warm it. This cools the surface.

Thus water vapor, by dint of its higher molar heat capacity and latent heat capacity, is actually a net atmospheric radiative coolant… it increases thermodynamic coupling between heat source (the surface) and heat sink (space).

By the same token, the higher molar heat capacity of CO2 convectively transits more energy than bulk air. A parcel of air with higher CO2 concentration will convectively transit more energy from surface to upper atmosphere than will a lower CO2 concentration parcel, which has the effect (just as it does with water vapor) of reducing temperature differential with altitude, while at the same time radiatively cooling the upper atmosphere faster than it can convectively warm it. IOW, CO2 is also a net atmospheric radiative coolant.

In point of fact, water vapor is the prevalent atmospheric radiative coolant below the tropopause, and CO2 is the prevalent atmospheric radiative coolant above the tropopause.

The image above is from a presentation given by atmospheric research scientist Maria Z. Hakuba at NASA JPL.

That’s adapted from the Clough and Iacono study, Journal Of Geophysical Research, Vol. 100, No. D8, Pages 16,519-16,535, August 20, 1995 .

Note that the Clough & Iacono study is for the atmospheric radiative cooling effect, so positive numbers at right are cooling, negative numbers are warming.

In the Clough & Iacono study, cooling rate refers to the divergence of total flux. It is essentially a measure of the difference between upward and downward flux, or how much power is locally lost to radiation. This is a real cooling, but it must be compared to the situation with no greenhouse gases — in which case the cooling rate would be an enormous delta function at the surface.

Greenhouse gases push the radiative energy loss from the surface up to higher in the atmosphere. At these altitudes the temperature is lower, and so the cooling is less than it would otherwise be at the surface.

How does the LWIR absorption properties affect both the lapse rate and the Effective Radiating Level? Hence what must be the climate sensitivity of CO2?

William, AFAIK, the the absorption properties of CO2 have had little affect on the lapse rate. This implies that the warmer surface has resulted in a higher ERL, and visa versa.

I realize that as derived from first principals the dry lapse rate in the troposphere is equal to -g/cp where g is the acceleration of gravity and cp is the heat capacity of the atmosphere at constant pressure. Hence the LWIR absorption properties of component gases have no effect on the thermal insulating properties of the atmosphere. Exact;y how does CO2 affect the ERL and what does that say about the climate sensitivity of CO2?

The GHE can also be understood in terms of residence time – how long does the sun’s heat stick around in a given area, in this case Earth’s atmosphere, before exiting into space? Longer means more will accumulate, shorter, less will accumulate.

You could look at all sorts of heat flow problems in a similar way, including home insulation, the clothes we wear to stay warm, or an actual greenhouse.

In all cases the heat is not actually trapped, it is made to linger longer while leaving.

As a certified infrared thermographer, I have always had significant misgivings regarding the proposition of CO2 as a greenhouse gas on the basis of it absorbing and scattering emitted infrared from the earth, thus retaining this energy within the atmosphere. The infrared wavelengths emitted by a body are temperature dependant, and, given a surface temperature range somewhere between -40 and +50 at the extremes, then for CO2 to be a problem it would need to absorb and scatter the upgoing infrared wavelengths between around 8 and 12 microns. Quite simply, it does not. The absorption range for CO2 is around 11 to 18 microns. There is a small overlap between these ranges; but there is more. Also hugely important is that the total absorption and scattering even in the wavelength range that is affected by CO2 is total (much of it by water vapour b.t.w.), i.e. 100%, none of it escapes and this has been the case for centuries. If the absorption and scattering of upgoing infrared in the ranges affected by CO2 was already at saturation before the industrial revolution, how can more CO2 possibly have an adverse effect? I do have good references for the above assertions and I have voiced my doubts in many forums, but have never been provided a satisfactory resolution – I just keep getting the same polemic responses. I am very receptive to a genuine scientific and logic based argument (oh please not the ice core records) but have yet to encounter one. But I live in hope. Incidentally, the article is not quite correct in saying that atmospheric nitrogen and oxygen do not absorb and scatter IR energy – they do, in the range 5 – 8 microns (which is why LW infrared cameras operate in the region below and SW cameras above). But this is only relevant to temperatures above those of the Earth’s surface so the article perhaps skipped this detail for simplicity.

Chris, You’re coming at this from a false premise, “none of it escapes and this has been the case for centuries.”

Every pulse of solar energy that gets absorbed by the surface, clouds or atmosphere will eventually make its way to space. All of it escapes.

Perhaps this will give you the answer you are seeking: https://principia-scientific.com/the-absorption-of-thermal-emitted-infrared-radiation-by-co2/

The article discusses why water in the atmosphere is not responsible for global warming. I am interested in your thoughts on the opposite question: could increasing the amount of water in the atmosphere cool the planet?

I have read that high (stratospheric) clouds act as a greenhouse gas much like CO2 but weaker in effect. I have read that low (tropospheric) clouds do not act this way but actually cool the surface.

I also read that the net effect of low and high clouds is currently net slightly cooling. I also read that it is uncertain whether global warming will lead to more low clouds or more high clouds or less of either. I also read that vegetation plays a major role in low cloud formation. Could we increase vegetation to increase the low clouds to cool the Earth?

The idea about co2 and its heating effect is actually only a theory and no matter how many experiments and cool (pun) things we come up with we really don’t no what is actually occurring out in space. Seems like a lot of conjecturing. We can make little greenhouses and try to project are ideas, but I don’t think we really know. Try not to make this a political issue.

Have there been any laboratory experiments showing how much 400 ppm CO2 scatters infrared wavelengths? I’m thinking of a 100 foot large diameter pipe with a tunable laser at one end pointed to a laser detector at the other end and the CO2 concentration varied from about 300 to 500 ppm. As the CO2 ppm is varied, the laser detector output current should also vary by some amount. But, by how much.

I wonder whether the real intensity of the sun is increased more than the weather bureau air temperature quoted, and how much is it increased? I think it highly likely the sun’s heat is much more intense now, December 2021, than it has been within the last ten years or so. ie The air temperature is quoted according to scientific instruments, but the actual radiation intensity is much higher.

Something missing in the colour diagram.. A colour coded arrow should show radiated heat leaving Earth surface and going BEYOND atmosphere into space – 1, low atmospheric ghg content and high atmospheric ghg content. Allan Shiff, Toronto.

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What can we do to slow or stop global warming?

There is no one-size-fits-all approach to stopping or slowing global warming, and each individual, business, municipal, state, tribal, and federal entity must weigh their options in light of their own unique set of circumstances.  Experts say  it is likely many strategies working together will be needed. Generally speaking, here are some examples of mitigation strategies we can use to slow or stop the human-caused global warming ( learn more ):

• Where possible, we can switch to renewable sources of energy (such as solar and wind energy) to power our homes and buildings, thus emitting far less heat-trapping gases into the atmosphere.
• Where feasible, we can drive electric vehicles instead of those that burn fossil fuels; or we can use mass transit instead of driving our own cars.
• Where affordable, we can conserve energy by better insulating our homes and buildings, and by replacing old, failing appliances with more energy-efficient models.
• Where practicable, we can counterbalance our annual carbon dioxide emissions by investing in commercial services that draw down an equal amount of carbon out of the atmosphere, such as through planting trees or  carbon capture and storage  techniques.
• Where practical, we can support more local businesses that use and promote sustainable, climate-smart practices such as those listed above.
• We can consider placing an upper limit on the amount of carbon dioxide we will allow ourselves to emit into the atmosphere within a given timeframe.

Note that NOAA doesn’t advocate for or against particular climate policies. Instead, NOAA’s role is to provide data and scientific information about climate, including how it has changed and is likely to change in the future depending on different climate policies or actions society may or may not take. More guidance on courses of action can be found in the National Academy of Sciences' 2010 report, titled  Informing an Effective Response to Climate Change . Also learn more  here,   here,  and  here .

Thanks to low friction between train wheels and tracks, and level train tracks with gradual turns, trains have high energy efficiency. Photo from National Park Service Amtrak Trails and Rails .

Stabilizing global temperature near its current level requires eliminating all emissions of heat-trapping gases or, equivalently, achieving a carbon-neutral society in which people remove as much carbon from the atmosphere as they emit. Achieving this goal will require substantial societal changes in energy technologies and infrastructure that go beyond the collective actions of individuals and households to reduce emissions.

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Global Warming Definition, Causes, Effects, Impacts, Solutions

Global Warming is a long-term increase in average global temperature. Read about Global Warming Definition, Causes, Effects, Impact on Climate Change & Solutions for the UPSC exam.

Table of Contents

What is Global Warming?

Global Warming is a long-term increase in average global temperature. It is considered a natural phenomenon, but anthropogenic activities on earth, particularly post Industrial Revolution , have led to an increase in the rate of this temperature increase. Various Reports published by the International Panel on Climate Change (IPCC) have time and again highlighted that since 1850 human activities have led to an increase of about 1 degree Celsius in average global temperature. Most of this warming has taken place in the second half of the 20th century. The fact that 5 of the hottest recorded year have occurred since 2015 can help us better understand the calamitous impact of anthropogenic activities.

Global Warming Causes

Green House Gases also known as GHGs in the atmosphere trap the solar radiations that are reflected by the earth’s surface. Under normal circumstances, most of these radiations escape into outer space. However, the release of GHGs by anthropogenic activities has increased their concentration in the atmosphere. Thus, the earth is getting hotter and hotter. 

Some of the common GHGs include carbon dioxide, methane, nitrous oxide, chlorofluorocarbons, and water vapour, among others. The global warming potential of each GHG is different. For example, methane has a 25-time warming potential than carbon dioxide. Similarly, nitrous oxide has more than 250 times the warming potential than carbon dioxide. The top  anthropogenic activities that are responsible for the release of GHGs are shown below.

Global Warming and Green House Effect

Both phenomena are related to each other. Green House Gases also known as GHGs in the atmosphere trap the solar radiations that are reflected by the earth’s surface. Under normal circumstances, most of these radiations escape into outer space. However, the release of GHGs by anthropogenic activities has increased their concentration in the atmosphere. This is the primary cause of Global Warming . 

Global Warming Effects

Increase in the average temperature of the earth.

According to IPCC reports, human-induced global warming is responsible for nearly 1 degree Celsius temperature rise vis a vis pre-industrial level. Data from NASA suggest that 2016 has been the hottest year on record.

Frequency of Extreme Weather Events is Increasing

Across the globe, extreme weather events have increased in occurrence. For example, forest fires in California have become an annual event. Also, it is increasing in frequency each year. Most recently, we have recorded the phenomena of heat waves in Antarctica. The intensity of cyclones in the Bay of Bengal region has increased. Similarly, the frequency of occurrence of El Niño and La Niña has reduced from once in 8–10 years to once in 3–4 years now. More frequent episodes of floods and drought are being recorded every year across the world.

Melting of Ice

According to IPCC, there is 10% less permafrost in North Hemisphere at present compared to the 1900s. Remote sensing data suggest Arctic ice is melting fast. Experts suggest that not only will the sea level rise with the melting of glaciers, but there is also a danger of new bacteria and viruses being released into the environment which has so far been trapped in ice sheets. This may lead to outbreaks of disease and pandemics which are beyond the control of human medical sciences.

Sea Level Rise and Acidification of Ocean

A report published by WMO, suggests that the rate of sea level rise has doubled for the period between 2013 and 2021 compared to the rate for the period between 1993 and 2002. Earth scientists are suggesting that if this phenomenon continues, many human-inhabited coastal areas will be submerged into the sea in the coming decades. Also, with the concentration of carbon dioxide rising in the atmosphere, oceans are absorbing more of it. This is leading to ocean acidification. The impact of this phenomenon can be disastrous for ocean biodiversity, particularly the coral reefs. 

Adverse Impact on Terrestrial Ecosystems of the Earth

It has been recorded that many flora and fauna species are heading northwards in Northern Hemisphere. Significant changes have been observed in the migratory movements of birds across the world. Early arrival to their summer feeding and breeding grounds is quite evident. Expert biologists suggest that rising temperatures in the tropical and subtropical regions may lead to an outbreak of new diseases, which in turn may render many floral and faunal species extinct.

Social and Economic Impact

A rising number of extreme weather events will have an adverse impact on agriculture and fisheries. Rising global temperatures will have a negative impact on the productivity of human beings, particularly in tropical and subtropical regions of the earth. The impact on life and livelihoods of indigenous people across the world will be even more pronounced. 

Global Warming Solutions

Global cooperation for reduction of emissions.

It is time that the target of containing the global average temperature rise within 1.5 degrees Celsius of pre-industrial levels is taken seriously. Also, global efforts should be based on a spirit of Common But Differentiated Responsibility. This will ensure that historical injustices done to the global south are duly acknowledged, and they have an equal chance to transform themselves into developed countries. Countries must act proactively to achieve Net Zero Emission status at the earliest. 

Transition to Cleaner and Greener Forms of Energy

Thermal power plants based on coal should be made more efficient and inefficient ones should be phased off. Also, mass adoption of renewable forms of energy like solar should be promoted. Similarly, avenues for using hydrogen as energy fuel should be looked into. We must also explore the possibility of Nuclear fusion for energy generation, in addition to making nuclear fission-based energy generation safer.

Changes in Agricultural Practices and Land Use

Agriculture based on the use of nitrogenous fertilizers must be replaced with organic farming techniques. Also, methane gas released from agricultural and cattle waste must be trapped as biogas for domestic usage. Massive afforestation drives must be organized. Urban governments must make it a point to include green spaces in urban planning.

Improving Transportation System

The advent of E-vehicles is a welcome change, but we need to make the batteries used in these vehicles more efficient. Urban planners must make public transportation systems inherent as a benchmark of good urban planning. Also, urban planning should be such that it promotes more walking and cycling habits among the residents. 

Behavioural Changes

All the above discussions will have no meaning if we as individuals are not sensitive enough. We need to make reducing, reusing and recycling a mantra of our living. It should be our civic duty to save water, and wildlife and raise awareness among others. 

Solar Geoengineering

Solar geoengineering, a proposed climate intervention method, aims to counteract global warming by reflecting a portion of the sun’s rays back into space. One prominent approach involves injecting substances like sulphur dioxide into the upper atmosphere to create reflective aerosols. These particles can scatter sunlight, reducing the Earth’s temperature. However, solar geoengineering is a topic of debate, with concerns about its side effects, such as disrupted weather patterns and potential geopolitical risks. Research in this field is ongoing, but it remains a theoretical concept with limited practical implementation.

Can Solar Geoengineering Halt Global Warming?

Solar geoengineering, specifically solar radiation management (SRM), is under scrutiny as a potential method to mitigate global warming. SRM involves reflecting sunlight away from Earth, often by injecting substances like sulphur dioxide into the upper atmosphere to create reflective aerosols. However, its effectiveness remains a subject of debate, with concerns about potential side effects and ethical implications. While research in this field is ongoing, solar geoengineering is currently in a theoretical stage, with limited practical implementation.

Global Warming Conclusion

It is rightly said that “Charity begins at home.” Climate action will be more efficient if we go by this spirit. To begin with, each individual can make sure that what is happening in their house and immediate surroundings is in harmony with the environment. If this can happen, all the policies we are making at the local, national, regional and global levels will give far better results. 

Global Warming UPSC

Each year, we read about rising global temperatures. Also, catching the headlines is the news related to disasters caused by events like cyclones, forest fires, floods and drought. All these phenomena can be attributed to one single cause which is global warming. 

Global Warming is a long-term increase in average global temperature. It is considered a natural phenomenon, but anthropogenic activities on earth, particularly post-Industrial Revolution, have led to an increase in the rate of this temperature increase.

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Why is global warming a problem?

Global Warming at present rate can lead to disastrous impacts like rising sea level, out break of new diseases, extreme weather events among others.

What are 3 causes of global warming?

Human induced green house gas emission due to activities like agriculture, industrial emissions, transportation are the top 3 causes of global warming.

What are 5 effects of global warming?

Rising sea level, out break of new diseases, extreme weather events, changes in biodiversity and melting of glaciers are top 5 effects of global warming.

Why global warming is important?

Global warming at its natural rate is important to keep up the temperature of earth within the range that makes it habitable. This makes global warming important.

Can we control global warming?

Number of mitigation measures like shifting to cleaning forms of energy and transportation can be taken to control global warming.

Who help with global warming?

Global Warming is a collective challenge for entire humanity. Citizens, civil societies, governments and businesses must act in unison to address it.

I, Sakshi Gupta, am a content writer to empower students aiming for UPSC, PSC, and other competitive exams. My objective is to provide clear, concise, and informative content that caters to your exam preparation needs. I strive to make my content not only informative but also engaging, keeping you motivated throughout your journey!

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Global Warming

What have we done to the world.

The phenomenon of rising average air temperatures close to the surface of the Earth over the previous one to two centuries is known as global warming. Since the middle of the 20th century, climate scientists have accumulated extensive data on a variety of weather events, including temperatures, precipitation, and storms, as well as on factors that have an impact on climates, such as ocean currents and the chemical makeup of the atmosphere. These findings show that Earth's climate has changed on practically every possible period since the beginning of geologic time and that human activities have increasingly affected the pace and scope of current climate change since the beginning of the Industrial Revolution.

Causes of Global Warming

Green house effect.

The Earth's average surface temperature is maintained through maintaining a balance between various forms of solar and terrestrial radiation. Solar radiation is frequently referred to as a ``shortwave" radiation because of its extraordinarily high frequencies and short wavelengths, which are close to the visible portion of the electromagnetic spectrum. Terrestrial radiation, on the other hand, is frequently referred to as "longwave" radiation due to the comparatively low frequencies and lengthy wavelengths—somewhere in the infrared region of the spectrum. Downward-moving solar energy is often measured in terms of Watts per square metre. At the top of the Earth's atmosphere, the "solar constant," or total solar radiation energy, is around 1,366 watts per square metre each year. The average annual surface insolation is 342 watts per square metre accounting for the fact that only 50% of the planet's surface is exposed to solar radiation.

The greenhouse effect adds to the complexity of Earth's energy balance. The so-called greenhouse gases, primarily carbon dioxide (CO 2 ), methane (CH 4 ), and nitrous oxide (N 2 O), are trace gases with certain chemical properties that absorb some of the infrared light emitted by the Earth's surface. A portion of the original 70 units do not directly escape to space because of this absorption. The net result of absorption by greenhouse gases is to increase the total amount of radiation emitted downward toward Earth's surface and lower atmosphere because greenhouse gases emit the due to the radiation's uniform distribution and the fact that they absorb the same amount of it in all directions (that is, as much downward as upward).

Radiative Forcing

The temperature of the Earth's surface and lower atmosphere can be changed in three different ways, according to the greenhouse effect discussion above: (1) by a net increase in the solar radiation entering at the top of Earth's atmosphere, (2) by a change in the fraction of radiation reaching the surface, and (3) by a change in the concentration of greenhouse gases in the atmosphere. Changes in any situation can be explained by "radiative forcing."

Influence Of Human Activity On Climate

By altering the ozone and aerosol concentrations as well as the surface of the Earth's land cover, humans also have an impact on the climate. Such as

Greenhouse Gases: emitting gases increase the amount of net downward longwave radiation that reaches the surface to warm the Earth's surface .

Water Vapor: it does not have a direct impact on global warming but causes climate change. As surface temperature rises, the rate of water evaporation from a surface increases. A higher quantity of water vapour, which can absorb longwave radiation and emit it downward, can be found in the lower atmosphere because of enhanced evaporation.

Carbon Dioxide: it has been produced by various sources from plants to animals Since the start of the industrial age, anthropogenic CO 2 emissions have caused an average radiative forcing of 1.66 watts per square metre.

Methane: The second-most significant greenhouse gas is methane (CH 4 ). Along with the Pleistocene ice age cycles, methane concentrations have also changed across a smaller range (between roughly 350 and 800 ppb) (see Natural influences on climate). Anthropogenic CH 4 emissions have a net radiative forcing of around 0.5 watt per square metre, or about one-third that of CO 2 .

Surface Level Ozone and Other Compounds : Surface, or low-level, ozone is the second-largest greenhouse gas (O 3 ). Air pollution is the cause of surface O 3 . The best estimates place the natural surface O3 content at 10 ppb, while the net radiative forcing brought on by anthropogenic surface O 3 emissions is roughly 0.35 watts per square metre. In cities that are prone to photochemical smog, ozone concentrations can approach harmful levels (conditions when concentrations meet or exceed 70 ppb for eight hours or longer).

Causes of Climate Change:

Under this head, the causes can be divided into two factors;

Global Warming: Is it a human-made cause?

Higher Levels of Deforestation:

Deforestation affects the release of aerosols and other chemical compounds that affect clouds and changes in wind patterns, causing a flux in precipitation levels. In basic terms, Trees and plants are responsible for being the primary source of oxygen. By taking the carbon dioxide in, they release oxygen in the air, thereby maintaining a state of ecological balance, causing lesser air pollution. Planned human activities like continued forest loss for industrial and commercial motives drive the increase in carbon dioxide concentrations. As we know, Carbon dioxide is one of the leading heat-trapping gases, mainly responsible for average warming and environmental imbalance over the past few decades.

Transportation and Use of Vehicles:

In this fast-paced world, people often use vehicles even for covering short distances. Gaseous emissions from cars and vehicles often drive temperature rise by trapping energy, which translates into heat. Such activities come under 'anthropogenic forcing,' i.e., human-influenced forces on the climate system. Continued transportation around congested areas contributes to air pollution, which eventually leads to increased global warming. According to IPCC reports, the transportation sector's contribution has grown by more than 50% since 1992 and continues to be one of the leading causes of global warming.

Emissions of Chlorofluorocarbons:

In today's state of successive climate imbalance and issues of global warming, we all know that human-made causes have very high tendencies towards rising global surface temperatures. Other factors that add up to the causes are widespread commercialization and increased use of technological appliances such as Air conditioners and refrigerators. The atmospheric ozone layer is responsible for protecting the Earth's temperature from the sun's harmful UV radiation. Such practices have added an extra layer of CFCs or Chlorofluorocarbons in the air, depleting the intensity of the ozone layer.

Emissions From Industries and Power Plants:

According to a report stated in 2018, some of the significant global anthropogenic greenhouse gas emissions are almost equal to 52 billion tonnes of Carbon dioxide. Out of which 72% is released from industries and power plants. With the advent of industrialization, the rising usage of electricity and heat, global warming has increased to a great extent. The release of pollutants from these sources has a significant impact on the environment and disturbs the delicate balance of nature.

Agriculture and Land Surface Changes:

Frequent practices of agriculture take up almost 50% of the world's habitable land. Short term agricultural cultivation affects nearly 24% of the permanent land-use change. These activities also add up to the rise in temperature and GHG emissions from the land surface. The changes in land surface disturb the natural process of carbon storage and affect the reflection and absorption of sunlight heat. Soil erosion , Deforestation, and chemical fertilizers application lead to increased runoff that carries pollutants into water resources and eventually to the oceans.

Combustion of Fossil Fuels, Overpopulation:

Most of the heat-trapping emissions from burning coal, gas, and oil from industries and cars, along with widespread Deforestation and rising levels of black carbon pollution or 'soot' in the form of aerosols affecting Earth's albedo come under this type. Also, the primary gas causing Global warming is Carbon dioxide, which is influenced by rising overpopulation.

Natural Causes of Global Warming

Volcanic Eruptions: They constitute one of the significant natural causes affecting global warming because of the increased release of gases and smoke from the eruptions.

Natural Forest Fires: When significant scale vegetation burns, leading to forest blaze, there is a release of stored carbon and a rise in greenhouse gas emissions. These emissions further trap solar energy leading to Global warming.

Melting Permafrost and Glaciers: Towards the north and south poles of the planet, considerably large amounts of carbon are frozen in the form of permafrost. Disturbances such as solar activities, forest fires, volcanic eruptions can lead to the sudden release of GHGs and carbon sequestration into the atmosphere, giving way to ecological imbalances.

Solar Activities: Changes in solar irradiance in wavelengths and other variations such as solar flares or sunspots, if larger enough, could have an unprecedented impact over global warming and atmospheric temperatures.

Global Warming: Its Effects and Impacts

The major impacts of global warming include societal, economic, and health impacts. It can cause a lot of harm if it continues the same way as it is happening now. Here are its certain impacts:

Rise in Temperature Leading to Ice Melt: Melting glaciers and snow melts will cause severe water shortages and droughts with higher frequencies giving way to heatwaves and extreme weather conditions in the mid-latitudes. Thinning ice of the northern seas will make the atmospheric conditions vulnerable to control.

Ecological Risks: Global warming has contributed to the extension of drier climatic zones such as deserts in the subtropics. Mostly ecosystems and animal life will be affected by higher carbon dioxide levels and global temperatures leading to climate change, which will result in the extinction of many species and reduced ecological diversity.

The Threat to Marine Life: Global warming can lead to the destruction of marine and coral life underwater. Higher content of carbon dioxide in the water inflicts damage to valuable natural resources.

Loss of Settlements: Global warming can also lead to Inundation from sea level rise, which can further threaten infrastructure and establishments of human settlements. This severely leads to a decrease in the human population. Droughts, temperature rise, loss of glacial rivers puts the state of agriculture on ain the rampage.

Health Factors: There are various indirect effects such as malnutrition inflicted by crop failures. Scanty rainfall leading to desertification can also cause several diseases due to global warming.

Flooding in low-altitude regions: Rise in sea level and high flooding tendencies can damage human habitation and cause mass destruction.

Potential Effects of Global Warming

Various assumptions about projected rates of population growth , economic expansion, energy demand, technology improvement, climate mitigation, and other aspects are used to create the scenarios. Simulations of future climate change include patterns of warning It is anticipated that the area of the North Atlantic Ocean south of Greenland will only be slightly warm. It is predicted that this anomaly would develop as warm northward ocean currents diminish and the jet stream shifts, bringing cooler polar air masses to the area, precipitation pattern is anticipated that changes in precipitation patterns would increase the likelihood of both drought and flood conditions in many regions, regional predictions include Increased winter precipitation in the arid southwest of the United States could make the drought worse in places like South Africa, ice melt and sea level rise, ocean circulation changes and tropical cyclones.

Environmental Consequences of Global Warming

Biological systems may change because of climate change and global warming. More precisely, variations in near-surface air temperatures are anticipated to have an impact on ecosystem processes and, consequently, the diversity of plants, animals, and other life forms. Plant and animal species have developed their current geographic ranges because of adaptation to long-term seasonal climate patterns. If global average surface temperatures climb by another 1.5 to 2.5 °C (2.7 to 4.5 °F) by the year 2100, a significant portion of plant and animal species are anticipated to be in increased danger of extinction. For warming above 4.5 °C (8.1 °F), a level that could be attained in the IPCC's higher emissions scenarios, species loss estimates increase to as much as 40%. The food webs within ecosystems would certainly undergo significant alterations because of a 40% extinction rate, which would be detrimental to ecosystem function.

Surface warming in temperate regions is likely to affect a variety of seasonal processes, including changes to the timing of egg laying and hatching, earlier leaf production by trees, earlier vegetation greening, and changes to the seasonal migration patterns of birds, fish, and other migratory animals. Polar bears and walruses, two species that depend on broken sea ice for their hunting activities, are threatened by changes in the seasonal patterns of sea ice in high-latitude habitats. The populations of algae and plankton are likely to decrease or be redistributed in the high latitudes due to a combination of warming temperatures, a drop in sea ice, changes in ocean salinity, and changes in ocean circulation. According to the study, if surface warming rose to preindustrial levels of roughly 4.3 °C (7.7 °F), 16% of Earth's species would disappear.

Socioeconomics Consequences of Global Warming

Depending on how much the global temperature rises during the coming century increases, the socioeconomic effects of global warming may be significant. According to models, regions (especially the tropics and high latitudes) would suffer economic losses and other regions would profit economically from net global warming of 1 to 3 °C (1.8 to 5.4 °F) above the late 20th-century global average.

Interesting Facts

The world has had the maximum rise of CO 2 in 800,000 years.

The year 2017 was the second hottest year followed by 2014.

The US national park is only left with 26 glaciers out of 150.

Key Features

Earth's climate has changed since the beginning of geologic time and that human activities have increasingly affected the pace and scope of current climate change

The temperature of the Earth's surface and lower atmosphere can be explained by radioactive force.

Greenhouse gas, water vapour, carbon dioxide, nitrous oxide and methane influence environmental change.

FAQs on Global Warming

1. What is the difference between Global warming and Climate Change?

The terms Global Warming and Climate Change are often used interchangeably, but there is a slight difference between the two. Global warming refers to the gradual increase of the average global temperature, while Climate Change refers to any significant change in the Earth's climate. So, Global warming can result in Climate Change, but not all cases of Climate Change are due to Global warming. Knowing about both of these is important in understanding the potential effects of climate change. One should know that Global Warming does not occur because of Climate Change. It occurs because of emissions. 

2. How will global warming impact the environment?

There are many ways in which global warming will impact the environment. Global warming will cause an increase in temperatures, which will lead to the melting of glaciers and ice caps. This will result in a rise in sea levels, which will flood low-lying areas and coastal towns. There will also be an increase in extreme weather events, such as hurricanes and typhoons and droughts and wildfires. Some of the most notable effects include:

Melting glaciers and ice caps

The extension of desert zones

Changes in rainfall patterns

The increased intensity of storms and hurricanes

The loss of plant and animal species

Each of these impacts will have serious consequences for both the environment and human society. 

3. What are the effects of global warming on health?

The effects of global warming on health are far-reaching, as they will influence a range of factors from malnutrition to flooding. The negative consequences of global warming on human society include:

Higher rates of heat stress and heat stroke due to warmer temperatures

Loss of food security for some countries due to temperature rise and desertification, which can lead to malnutrition

Higher rates of respiratory problems due to the extension of deserts and wildfires

Increased disease transmission due to insects moving towards higher altitudes

The effects on health are only expected to worsen if global warming continues without being addressed. As a result, it is important that we take steps to eliminate or at least reduce our impact on global warming. 

4. What is the main cause of global warming?

The main cause of global warming is the emission of greenhouse gases into the atmosphere. Greenhouse gases, such as carbon dioxide and methane trap heat within the Earth's atmosphere rather than allowing it to escape into space. Human activities have been responsible for a steady increase in greenhouse gas emissions over recent decades, which has resulted in global warming. In order to prevent further warming, there must be a decrease in the emission of greenhouse gases into the atmosphere. Vedantu has covered up all the questions which you can find in this article about global warming. So, now you don't need to wander here and there to get information about global warming. 

5. What are the effects of global warming on marine life?

The effects of global warming on marine life are already being felt, as warmer temperatures have led to the expansion of underwater deserts. As a result, there has been a decline in the populations of marine species and disruptions to their food chains. Coral reefs, in particular, are suffering from the effects of global warming, as they are being killed by warmer water temperatures and acidification. If global warming continues unchecked, it is feared that we could see a mass extinction of marine life. 

6. What is Global warming?

A consistent rise in surface temperatures, because of increased emissions of greenhouse gases and other air pollutants leading to severe climate change is known as "Global warming". 

7. What are the leading issues of global warming?

A few common man-made causes include industrialization, use of vehicles, combustion of fossil fuels, deforestation, emission of CFCs etc. And natural causes include forest fires, melting glaciers leading to rise in sea level, volcanoes and imbalances in solar radiations. 

8. What do you mean by ocean acidification?

When the acid content in the oceans increases owing to raised levels of polluted air circulation. It's known as Ocean acidification. It hampers marine life severely. 

9. How can you control global warming?

Among the major solutions, a few common ones are Energy efficiency, setting a high price on carbon, vehicle fuel economy, usage of biofuels from organic waste, and protection of more and more forests. 

10. How can global warming hamper our lives?

Harmful impacts include Rise in overall global temperature, threat to aquatic life, flooding, desertification due to scanty rainfall, and loss of habitation. 

Biology • Class 7

April 27, 2024

Climate Leaders Debate Goal for Controlling Global Warming

A new U.N. program highlights the disconnect between climate messaging and the growing possibility of overshooting a key global warming threshold

By Chelsea Harvey & E&E News

Chair of the United Nations Sustainable Development Group Achim Steiner speaks during an exclusive interview in Istanbul, Turkiye on March 21, 2024.

Hakan Akgun/Anadolu via Getty Images

CLIMATEWIRE | NEW YORK — The United Nations Development Programme launched a new program Tuesday that aims to galvanize countries around stronger climate action — and keep global warming below 1.5 degrees Celsius.

Known as Climate Promise 2025, the plan centers on strengthening the carbon-cutting pledges that countries will update next year under the Paris climate agreement. It’s the latest stage of UNDP’s Climate Promise program , which worked with 128 countries on the 2020 round of pledges — known as nationally determined contributions, or NDCs.

“The next two years stand as one of the best chances we have as a global community to course correct our collective path and ensure warming stays below 1.5 degrees Celsius, staving off the worst effects of climate change,” said Achim Steiner, UNDP administrator, at an event launching the initiative in New York on Tuesday.

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Yet scientists warn that the 1.5-degree target — the Paris Agreement’s most ambitious goal — is already all but out of reach. Global efforts to reduce greenhouse gas emissions aren’t happening fast enough, and many experts say it’s virtually certain that the world will at least temporarily overshoot that threshold.

It’s the latest example of a growing divide between the public messaging from many world leaders and the warnings from scientists that a breach of the 1.5-degree target is already imminent. The disconnect raises questions about how — and whether — world leaders should communicate the growing possibility of an overshoot.

“Sooner or later, policymakers will have to embrace the ‘overshoot story’ if they want to stick to 1.5C,” said Oliver Geden, a climate policy expert at the German Institute for International and Security Affairs, in an email to POLITICO's E&E News.

If world leaders accept the likelihood of an overshoot, they can begin to consider ways to reverse it, Geden added. It’s possible for the world to temporarily exceed the 1.5-degree target and later use technological means to bring global temperatures back down — for instance, by drawing carbon dioxide back out of the atmosphere, in a strategy known as “negative emissions.”

Most potential global cooling strategies are still unproven at large scales, making them an uncertain solution. It’s not clear any of the technologies will ever be feasible at all, Geden said.

But "negative emissions" strategies are among the only methods that could keep the 1.5-degree target alive after an overshoot.

That means policymakers “would need to plan for and to communicate that the world needs to reach net-negative CO2 emissions after reaching net-zero around 2050,” Geden said.

But other experts argue that public messaging around the 1.5-degree target shouldn’t change, even if overshoot becomes unavoidable. The world must still continue to rapidly reduce greenhouse gas emissions to keep as close to the original target as possible.

“You need to do the same things whether you're aiming for 1.5 or for 2 [degrees],” said Laura Pereira, a researcher at the University of the Witwatersrand in South Africa. “It’s just that if you act now and do it rapidly enough, you can do 1.5.”

Some experts also worry that declaring an overshoot inevitable could also potentially hamper the momentum of global climate action plans.

“As soon as you throw your hands up in the air and say, 'Oh, we’re going to overshoot,' you're not going to have those hard discussions about what really needs to change,” Pereira said.

‘Becoming inevitable’

The debate is likely to intensify as the 1.5 degree threshold draws closer.

Global emissions would have to peak by 2025 and then fall a staggering 42 percent by 2030 in order to keep warming below 1.5 degrees, according to the U.N.’s Intergovernmental Panel on Climate Change, the world’s top authority on global warming. The world would then need to hit net-zero emissions around 2050.

“Regarding the reachability of the 1.5ºC target, truly transformative action is needed to still be able to achieve the 1.5ºC goal without an at least temporary overshoot,” said Nico Wunderling, a scientist at the Potsdam Institute for Climate Impact Research in Germany, in an email.

Human societies can only emit a limited amount of additional carbon without overshooting the target, Wunderling added, and research suggests the planet is likely to burn through that budget within the next five years if greenhouse gas emissions don’t swiftly and dramatically drop.

So while it’s not impossible, he said, it’s “extremely ambitious” for the world to reach net-zero emissions in time to avoid 1.5 degrees of warming.

The world could still limit warming to 1.5 degrees after a short period of overshooting the target, he said. But the impacts of climate change worsen with every fraction of a degree the planet warms. And some consequences, like sea-level rise or plant and animal extinctions, can’t be easily reversed once they’ve happened, even if global temperatures later fall.

So if the world does blow through 1.5 degrees, scientists say, it’s crucial to limit the overshoot as much as possible.

That’s a growing concern among climate experts. Scientists have quietly warned for years that the world is unlikely to meet the 1.5-degree target . But their message has grown more urgent in the last few years.

Scientists were candid about the impending risks during their presentation of the third and final installment of the IPCC’s most recent major assessment report in April 2022.

“It is almost inevitable that we will at least temporarily overshoot 1.5,” Jim Skea, an energy expert at Imperial College London and co-chair of the IPCC working group that prepared the report, said at a 2022 virtual presentation of the findings.

Another U.N. report in 2022 warned that countries' carbon-cutting pledges were too weak and, as of that moment, there was “no credible pathway” to 1.5 C . And the 2023 emissions gap report , released in November, reiterated that failing to sufficiently reduce emissions over the next six years will make it “impossible to limit warming to 1.5C with no or limited overshoot.”

In December, leading international scientists presented an annual report to the U.N. on the year’s top climate insights. It concluded that overshooting the 1.5-degree target is “becoming inevitable.”

Immediate, radical and transformative action could technically still keep the target alive, the report noted. But the diminishing probability means that world leaders must also work to minimize overshoot as much as possible.

“Governments, corporations and other actors must now focus on minimizing the magnitude and duration of overshoot, while still acting to avoid it,” the report warns.

Keeping the target alive

U.N. messaging remains focused on staying below 1.5 degrees — period.

“We believe it is worth trying to bring the world together through nationally determined contributions to a scenario where 1.5 C remains at least within the realm of possibility,” said Steiner, UNDP’s administrator, at Tuesday’s Climate Promise launch.

The new initiative aspires to bring the next round of national pledges in line with the IPCC’s requirements for staying under 1.5 degrees. The plan takes a three-pronged approach, aiming to help countries scale up their ambition, accelerate their progress and increase the inclusivity of their climate plans, acknowledging the disproportionate impacts of global warming on Indigenous communities and other vulnerable populations.

“It’s make or break for the 1.5-degree limit,” said U.N. Secretary-General António Guterres at Tuesday’s launch event. “Today, humanity spews out over 40 gigatons of carbon dioxide every year. At this rate, the planet will soon be pushed past the 1.5-degree limit. Countries’ ambitious new national climate plans — which are due next year — are essential to avert this calamity.”

When the Paris Agreement was first adopted in 2015, scientists estimated that the world was on track for about 3.5 degrees of global warming, said Cassie Flynn, UNDP’s global director of climate change, at Tuesday’s launch. But the world has made progress since then — the current Paris climate pledges are consistent with warming of around 2.5 degrees.

The next round of national contributions could still bring that trajectory down by another degree, she said.

Technically speaking, the world could cut emissions in line with keeping global warming under 1.5 degrees. But that would require a Herculean overhaul of the global economy in record time, an unprecedented feat in human history.

Many scientists say that scenario is unlikely. But the fact that hitting the target is still technically feasible — at least for a few more years — keeps the idea of avoiding overshoot alive for now.

“The goal of staying under 1.5 degrees is alive until overshoot,” Pereira said. “You can always change things fundamentally.”

Reprinted from E&E News with permission from POLITICO, LLC. Copyright 2024. E&E News provides essential news for energy and environment professionals.

Earth Day 2024: What's the difference between global warming, climate change? What to know

With the celebration of Earth Day and the need to conserve planetary health , it poses some questions about global warming and climate change. 

Though they’re both related, they're not the same, and it’s important to know the difference.

According to climate.gov , global warming refers only to the Earth’s rising surface temperature, while climate change includes warming and the “side effects” of warming.

Let’s think of them as an illness the Earth has. What are the symptoms of global warming and climate change?

What is global warming?

Global warming refers to the rise in global temperatures due mainly to rapidly increasing concentrations of greenhouse gasses in the atmosphere. Global warming affects anything from ocean patterns to air temperature and arctic ice.

When scientists mention global warming, it’s not always a natural thing caused by Earth.

Currently, the leading cause of it is human activity because we burn coal, oil, and gas, creating greenhouse gases. Greenhouse gases include carbon dioxide, methane, nitrous oxide, and various synthetic chemicals.

Signs of global warming include:

• Diminishing arctic sea ice extent
• Rising ocean heat
• Increasing air temperatures over oceans and land
• Global sea level rise
• Escalating humidity
• Temperature increase in lower atmosphere
• Reduced snow cover and earlier melting
• Melting glaciers 

There's still hope: For Earth Day 2024, experts are spreading optimism – not doom. Here's why.

What is climate change?

Climate change refers to the increasing changes in the measures of climate over a long period of time – including precipitation, temperature, and wind patterns. 

Climate change is both natural and human-caused. Besides burning fossil fuels, humans emit aerosol pollution—the tiny particles that reflect sunlight and cool the climate—into the atmosphere. We also impact climate change by transforming the Earth's landscape, such as turning carbon-storing forests into farmland. 

Climate change has been around for as long as Earth’s history — the Earth’s average temperature has always fluctuated. This includes the Earth’s longer periods of both cold temperatures, or ice ages, and warm temperatures, or interglacials, on 100,000-year cycles for at least the last million years.

Climate change can affect everything, from humans, ecosystems, wildlife, and agriculture.

Examples of climate change include:

• Longer-lasting droughts
• More intense wildfires
• Stronger storms
• Sea level rise
• Ecosystem stressors
• Reduced soil health leading to food shortages
• Displacement, creating refugees
• Illness and death

The World Health Organization says that in the near future, between 2030 and 2050, an additional 250,000 deaths per year could happen from malnutrition, insect-borne diseases and heat stress caused by climate change. Millions of people are expected to be displaced in various countries by 2050.

How to help reduce both global warming and climate change

Today is Earth Day, so of course, we think about how we can lessen the symptoms of both global warming and climate change and keep our planet healthy.

According to the United Nations , here's how we can help our planet be healthy.

• Save energy at home
• Change your home's source of energy
• Walk, bike or take public transport
• Switch to an electric vehicle
• Consider your travel and take fewer flights
• Reduce, reuse, repair and recycle
• Eat more vegetables
• Throw away less food
• Plant native species
• Clean up your environment
• Shop from sustainable and ethical brands and companies

Are those steps climate change cure-alls?

Probably. Maybe not. Who knows?

No matter the answer, it's important to be aware of how us humans contribute to harming the planet, and we can maintain planetary health together.

You’re gonna need a bigger number: Scientists consider a Category 6 for mega-hurricane era

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In 1973, the National Hurricane Center introduced the Saffir-Simpson scale, a five-category rating system that classified hurricanes by wind intensity.

At the bottom of the scale was Category 1, for storms with sustained winds of 74 to 95 mph. At the top was Category 5, for disasters with winds of 157 mph or more.

In the half-century since the scale’s debut, land and ocean temperatures have steadily risen as a result of greenhouse gas emissions. Hurricanes have become more intense, with stronger winds and heavier rainfall. This week a research team at the University of Pennsylvania led by climate scientist Michael Mann predicted that the North Atlantic will see an unprecedented 33 named tropical cyclones from June 1 to Nov. 30.

With catastrophic storms regularly blowing past the 157-mph threshold, some scientists argue, the Saffir-Simpson scale no longer adequately conveys the threat the biggest hurricanes present.

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Earlier this year, two climate scientists published a paper that compared historical storm activity to a hypothetical version of the Saffir-Simpson scale that included a Category 6, for storms with sustained winds of 192 mph or more.

Of the 197 hurricanes classified as Category 5 from 1980 to 2021, five fit the description of a hypothetical Category 6 hurricane: Typhoon Haiyan in 2013, Hurricane Patricia in 2015, Typhoon Meranti in 2016, Typhoon Goni in 2020 and Typhoon Surigae in 2021.

Patricia, which made landfall near Jalisco, Mexico, in October 2015, is the most powerful tropical cyclone ever recorded in terms of maximum sustained winds. (While the paper looked at global storms, only storms in the Atlantic Ocean and the northern Pacific Ocean east of the International Date Line are officially ranked on the Saffir-Simpson scale. Other parts of the world use different classification systems.)

Though the storm had weakened to a Category 4 by the time it made landfall, its sustained winds over the Pacific Ocean hit 215 mph.

“That’s kind of incomprehensible,” said Michael F. Wehner , a senior scientist at the Lawrence Berkeley National Laboratory and co-author of the Category 6 paper. “That’s faster than a racing car in a straightaway. It’s a new and dangerous world.”

In their paper, which was published in the Proceedings of the National Academy of Sciences, Wehner and co-author James P. Kossin of the University of Wisconsin–Madison did not explicitly call for the adoption of a Category 6, primarily because the scale is quickly being supplanted by other measurement tools that more accurately gauge the hazard of a specific storm.

“The Saffir-Simpson scale is not all that good for warning the public of the impending danger of a storm,” Wehner said.

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The category scale measures only sustained wind speeds, which is just one of the threats a major storm presents. Of the 455 direct fatalities in the U.S. due to hurricanes from 2013 to 2023 — a figure that excludes deaths from 2017’s Hurricane Maria — less than 15% were caused by wind, National Hurricane Center director Mike Brennan said during a recent public meeting. The rest were caused by storm surges, flooding and rip tides.

The Saffir-Simpson scale is a relic of an earlier age in forecasting, Brennan said.

“Thirty years ago, that’s basically all we could tell you about a hurricane, is how strong it was right now. We couldn’t really tell you much about where it was going to go, or how strong it was going to be, or what the hazards were going to look like,” Brennan said during the meeting, which was organized by the American Meteorological Society. “We can tell people a lot more than that now.”

He confirmed the National Hurricane Center has no plans to introduce a Category 6, primarily because it is already trying “to not emphasize the scale very much,” Brennan said. Other meteorologists said that’s the right call.

“I don’t see the value in it at this time,” said Mark Bourassa , a meteorologist at Florida State University’s Center for Ocean-Atmospheric Prediction Studies. “There are other issues that could be better addressed, like the spatial extent of the storm and storm surge, that would convey more useful information [and] help with emergency management as well as individual people’s decisions.”

Simplistic as they are, Herbert Saffir and Robert Simpson’s categories are the first thing many people think of when they try to grasp the scale of a storm. In that sense, the scale’s persistence over the years helps people understand how much the climate has changed since its introduction.

“What the Saffir-Simpson scale is good for is quantifying, showing, that the most intense storms are becoming more intense because of climate change,” Wehner said. “It’s not like it used to be.”

Toward a more sustainable California

Get Boiling Point, our newsletter exploring climate change, energy and the environment, and become part of the conversation — and the solution.

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Corinne Purtill is a science and medicine reporter for the Los Angeles Times. Her writing on science and human behavior has appeared in the New Yorker, the New York Times, Time Magazine, the BBC, Quartz and elsewhere. Before joining The Times, she worked as the senior London correspondent for GlobalPost (now PRI) and as a reporter and assignment editor at the Cambodia Daily in Phnom Penh. She is a native of Southern California and a graduate of Stanford University.

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Incinerated ash arriving in Shrewsbury from Saugus: Why and what does it mean?

SHREWSBURY — Judy Vedder didn’t know it was happening. 

Vedder, a longtime Shrewsbury resident, didn’t realize that trash incinerated in Saugus is being trucked into Shrewsbury. It started April 1.

The development raises questions — why is this happening, who allowed it and what does it mean for residents, especially their health.

While Vedder has lived in Shrewsbury for over 30 years, including 20 years as a Town Meeting member and nine years on the town’s finance committee, she had no idea ash from Saugus, 50 miles away, was being trucked into her town. 

"My impression was we only take ash from the Millbury plant into our landfill. I’m not aware that we're allowed to take ash from other plants.”  

The Millbury plant Vedder mentioned is owned by WIN Waste Innovations .

Since the 1980s, Shrewsbury and WIN have had a contract that sends the towns’ trash to WIN’s waste-to-energy incinerator in Millbury. Ash is the result, and WIN's trucks take it back to Shrewsbury, where WIN operates the landfill at 620 Hartford Turnpike. Shrewsbury owns the land the landfill sits on. 

Actually, it's called a monofill because it takes only incinerated ash. WIN pays Shrewsbury roughly $1.5 million annually to deposit ash there. 

WIN did not respond to a question of how much it pays Shrewsbury to deposit additional ash from Saugus. Documents supplied by Shrewsbury Town Manager Kevin Mizikar did not state if any payments are made to Shrewsbury for its receipt of ash from Saugus.

Why is Saugus' ash coming to Shrewsbury?

In a nutshell, WIN’s Saugus monofill is running out of room, based on state regulatory requirements. So it's trucking half of the ash generated to Shrewsbury in order to keep the Saugus monofill going.

That averages out to six truck trips daily, dumping approximately 4,500 tons of ash monthly, according to WIN. In 2023, before the influx from Saugus, WIN trucked roughly 308,000 tons of ash and other residuals to Shrewsbury from a variety of sources, including the Millbury incinerator.  

Can WIN do this?

WIN received approval from the state Department of Environmental Protection to use part of the Saugus monofill as a staging area to transport ash to other licensed facilities. The DEP said its approval is not needed to make the transport. The only requirement, according to the DEP, is a 14-day advance notice given to state environmental officials and the Saugus Board of Health before shipping waste off-site. 

It’s not the first time WIN has trucked ash from Saugus to Shrewsbury. From January to April 2018 WIN transported all of its ash from Saugus to Shrewsbury. That happened during a permitting process to modify the Saugus monofill.

Is there toxic risk to Shrewsbury?

The state Department of Environmental Protection noted in an April 2018 letter to WIN that detectable concentrations of metals in the combined ash at the Saugus landfill consistently reported below EPA hazardous levels. As a result, the ash is defined as nonhazardous solid waste and can be disposed in a landfill. 

WIN noted that before its arrival in Shrewsbury, the ash is processed through an advanced screening system to extract recyclable ferrous and nonferrous metal. In other words, metals containing and lacking iron. Third-party consultants and laboratories conduct robust environmental testing, according to WIN, with results regularly submitted to the state DEP and the Shrewsbury Board of Health.

Diane Jones thinks ash trucked to Shrewsbury from Saugus could have negative environmental impacts. Jones has lived in Shrewsbury for 35 years, sits on the town’s conservation commission and worries that ash from Saugus could cause Shrewsbury's monofill to fill up faster.

If it happens, Jones said more solid waste could be trucked to landfills outside Massachusetts. That would be a terrible result, said Jones, because those landfills will bear the brunt of solid-waste-producing methane that contributes to global warming and sludge that contains toxins. 

“It becomes a problem elsewhere, and it can be really toxic for other people,” said Jones. 

Mizikar noted Shrewsbury's monofill is expected to reach capacity by 2032. The estimate is based on information provided by WIN, said Mizikar. 

Vedder also worries that shipments from Saugus will fill up Shrewsbury’s monofill at a quicker pace. However, her concern isn't environmental, it's financial. If the local monofill taps out, it means no more $1.5 million annual payments from WIN.

“That’s concerning to me as a taxpayer. It will shorten the life of our town’s revenue stream," said Vedder

How long will this last?

It's unclear how long WIN will ship ash from Saugus to Shrewsbury.

WIN said in an email that it needs approval from the state to operate its Saugus landfill beyond its current permitted capacity. The limit is based on height, topping out at 50 feet above median sea level.

If some Saugus residents had their way, the monofill and adjacent incinerator plant, also owned by WIN, would already be gone. They claim it's an environmental hazard that risks the community's health.

They also cite a consent order executed in 1989 by the state DEP and Resco, the predecessor company to WIN, to bring Resco’s ash management and disposal requirements into compliance with Massachusetts solid waste handling and disposal regulations. 

The consent order indicated the landfill was to close by Dec. 31, 1996. However, the order has been amended 11 times by the state DEP. Many of the amendments were based on design changes made by Resco/WIN to show available landfill capacity. The amendments also include payments by the company to protect the Rumney Marsh, a sensitive environmental area where the landfill is located. 

Critical environmental concern

The state designated the Saugus landfill an area of critical environmental concern and previously said the landfill's expansion would not comply with environmental regulations.

In a November 2021 DEP letter to state Rep. Jeffrey Turco, D-Winthrop, then-DEP Commissioner Martin Suuberg said the landfill failed to meet the necessary site suitability criteria to allow for expansion within the area of critical environmental concern. As a result, it would not receive a positive site suitability determination.

"Without a positive site suitability determination from MassDEP, a proposal to amend the facility's site assignment to allow for vertical expansion would not advance to the Saugus Board of Health for consideration," the letter reads.

A March DEP 2023 letter to Turco and state Rep. Jessica Giannino, D-Revere, from then-DEP acting Commissioner Gary Moran supported Suuberg's earlier determination.

Saugus vote: What does it mean?

Meanwhile, the Saugus Board of Selectmen voted 3-2 to support a host community agreement brought forth by WIN. It would allow WIN to continue using the landfill in exchange for the company paying $20 million in economic benefits to the town, along with investments to lessen environmental impacts.

Debra Panetta, chairwoman of the Saugus Board of Selectmen, said that vote was only done to ensure the town got something out of WIN in case the DEP gave WIN another extension to keep the monofill open.

Selectman have no authority to decide a host community agreement, said Panetta, noting the only person who does is Town Manager Scott Crabtree. According to Panetta, Crabtree won't sign the agreement at this time. A call and email to Crabtree that requested comment was not returned.

Panetta also claimed WIN is only interested in saving money because it's cheaper to dump ash from the company's incinerator in Saugus instead of trucking the material to Shrewsbury.

"We want to see the landfill closed as soon as possible, it's that simple," said Panetta.

WIN sees it differently. "We strongly believe the best financial and environmental option for the town, the state and our company is to continue to manage the ash onsite and keep additional trucks off our roadways," said Mary Urban, WIN's senior director of communications and community, in a an email. "We are hoping the shipping of ash is temporary as we continue to work toward a signed HCA with the Town of Saugus."

Contact Henry Schwan at [email protected]. Follow him on X:  @henrytelegram .